Primary vaginal cancer: role of MRI in diagnosis, staging and treatment

Abstract

Primary carcinoma of the vagina is rare, accounting for 1–3% of all gynaecological malignancies. MRI has an increasing role in diagnosis, staging, treatment and assessment of complications in gynaecologic malignancy. In this review, we illustrate the utility of MRI in patients with primary vaginal cancer and highlight key aspects of staging, treatment, recurrence and complications.

The incidence of primary vaginal cancer increases with age, with approximately 50% of patients presenting at age greater than 70 years and 20% greater than 80 years.¹ Around 2890 patients are currently diagnosed with vaginal carcinoma in the USA each year, and almost 30% die of the disease.² The precursor for vaginal cancer, vaginal intraepithelial neoplasia (VAIN) and invasive vaginal cancer is strongly associated with human papillomavirus (HPV) infection (93%).^3,4 In situ and invasive vaginal cancer share many of the same risk factors as cervical cancer, such as tobacco use, younger age at coitarche, HPV and multiple sexual partners.^5–7 In fact, higher rates of vaginal cancer are observed in patients with a previous diagnosis of cervical cancer or cervical intraepithelial neoplasia.^7,8

As is true for other gynaecologic malignancies, vaginal cancer diagnosis and staging rely primarily on clinical evaluation by the International Federation of Gynecology and Obstetrics (FIGO).⁹ Pelvic examination continues to be the most important tool for evaluating local extent of disease, but this method alone is limited in its ability to detect lymphadenopathy and the extent of tumour infiltration. Hence, FIGO encourages the use of imaging. Fluorine-18 fludeoxyglucose-positron emission tomography (¹⁸F-FDG-PET), a standard imaging tool for staging and follow-up in cervical cancer, can also be used for vaginal tumours, with improved sensitivity for nodal involvement compared to CT alone.¹⁰ In addition to staging for nodal and distant disease, CT [simulation with three dimensional (3D) conformations] is particularly useful for treatment planning and delivery of external beam radiation. MRI, with its excellent soft tissue resolution, is commonly used in gynaecologic malignancies and has been shown to be accurate in diagnosis, local staging and spread of disease in vaginal cancer.^11,12 While no formal studies are available for vaginal cancer, in cervical cancer MRI actually alters the stage in almost 30% of patients.^13–15

Treatment planning in primary vaginal cancer is complex and requires a detailed understanding of the extent of disease. Because vaginal cancer is rare, treatment plans remain less well defined, often individualized and extrapolated from institutional experience and outcomes in cervical cancer.^1,16–19 There is an increasing trend towards organ preservation and treatment strategies based on combined external beam radiation and brachytherapy, often with concurrent chemotherapy,^14,20,21 surgery being reserved for those with in situ or very early-stage disease.²² Increasing utilization of MR may provide superior delineation of tumour volume, both for initial staging and follow-up, to allow for better treatment planning.²³

ANATOMY

The vagina is a 3- to 4- inch fibromuscular tube extending from the lower aspect of the cervix to the vulva, situated behind the urethra and bladder and in front of the rectum. The vagina is divided into three segments, important for classifying tumour location and lymphatic drainage (Figure 1). The lower third is below the level of the bladder base with the urethra anteriorly. The middle third is adjacent to the bladder base, and the upper third at the level of the vaginal fornices. The vaginal fornices are denoted as anterior, posterior and lateral with respect to the cervix (Figure 1).

Figure 1.

Anatomy of the vagina. (a) Anatomic division into segments. Sagittal T₂ weighted MR image delineates the three anatomic divisions of the vagina: (1) upper third, (2) middle third and (3) lower third. Within the upper third of the vagina, the anterior (labelled a) and posterior (labelled p) fornices can be seen. (b) Axial T₂ weighted MR image delineates the lateral vaginal fornices (asterisk) separated by the cervix, denoted with a c. (c) Vagina without gel. Axial T₂ weighted image shows three layers of the vaginal wall: the mucosa (large white arrow), the muscularis and submucosa (asterisk) and the adventitia (small white arrow). (d) Vagina with gel. Axial T₂ weighted image shows only two appreciable layers of the vaginal wall: the muscularis and submucosa (black arrow) and the adventitia (white arrow).

Lymph node drainage is important as vaginal cancer commonly involves lymph nodes even in early-stage disease, with reported rates 6–14% for Stage I and 26–32% for Stage II disease.^24,25 Moreover, inguinal lymph node involvement has been implicated in aggressive tumour behaviour and lower rates of survival.²⁶ Theoretically, the upper third of the vagina drains into the external iliac and para-aortic chain, the middle third into the common and internal iliac chains and the lower third into the superficial inguinal, femoral and perirectal nodal chains. However, these ascribed patterns of lymphatic drainage are highly variable and unreliable; hence, in patients undergoing surgery, sentinel lymph node mapping can be performed prior to lymph node dissection.²¹

PATHOLOGY

The most common tumour of the vagina is metastasis. Primary vaginal cancer, though, has two major histopathology types: squamous cell carcinoma (80%) and adenocarcinoma (15%). Melanoma, lymphoma and sarcoma are highly unusual, comprising the remaining 5%.^1,27 Squamous cell carcinoma arises from the vaginal mucosa, which is composed of oestrogen-sensitive stratified squamous epithelium. It is more common in postmenopausal females (median age, 60 years) and frequently involves the proximal third of the vagina.¹² Squamous cell carcinoma can also be multifocal when developing in a background of VAIN and has been reported in vulvovaginal lichen planus.²⁸ Adenocarcinoma, unlike squamous cell carcinoma, commonly affects younger patients (median age, 19 years) and is more likely to metastasize to the lungs and lymph nodes.⁵ One subtype, clear cell adenocarcinoma, is classically associated with in utero exposure to diethylstilboestrol and is found in 2% of exposed females.²⁹ The staging and treatment of vaginal cancer in this review will focus on squamous cell carcinoma and adenocarcinoma, the two most common histologic types.

CLINICAL STAGING AND PROGNOSIS

Vaginal cancer is staged and classified according to guidelines of the FIGO and the American Joint Committee on Cancer.⁹ The FIGO system is most commonly used and is summarized in Table 1.⁹ According to FIGO, tumours involving the cervix and vulva are considered cervical and vulvar malignancies, respectively, regardless of whether the epicentre of the tumour is in the vagina.

Table 1.

International Federation of Gynecology and Obstetrics (FIGO) staging of vaginal cancer

Stage	Description
Stage 0	Carcinoma in situ, intraepithelial carcinomaa
Stage I	Confined to the vagina
Stage II	Involvement of paravaginal tissue but not pelvic sidewall
Stage III	Extension to pelvic sidewall
Stage IV	Extension beyond true pelvis or bladder and/or rectal involvement
IVA	–Extension beyond pelvis, bladder or rectal invasion
IVB	–Distant organ metastases

Compiled from FIGO Committee on Gynecologic Oncology staging information.⁹

^aNo current role for imaging.

Prognosis correlates strongly with stage of disease. Relative 5-year survival in larger series range from 96% for Stage 0, 64–84% for Stage I, 53–58% for Stage II, 36% for Stage III and 18–36% for Stage IV.^16,30 In patients treated with definitive radiation, cause-specific survival ranges from 40 to 92% for Stage I, 35 to 78% for Stage II, 23 to 59% for Stage III and 0 to 25% for Stage IV.^16,31–37 Factors negatively associated with survival include advanced stage, larger tumour size, lower and middle vaginal tumours and older age (greater than 60 years), though tumour position has conflicting evidence.^{25,31,38–40} Recent studies have found that age, FIGO stage and MIB-1 are the primary independent prognostic factors for 5-year disease-free survival.⁴¹ MIB-1 index, or tumour expression of the proliferation-associated antigen Ki-67, is an immunocytochemical marker of mitotic rate and has been shown to be important in other gynaecologic cancers, specifically endometrial and cervical cancers.^30,42,43

Histologic type and primary tumour characteristics are also predictive of survival. For females with squamous cell carcinoma, 5-year survival is approximately 54%. For adenocarcinoma overall, survival is similar at 60%, though significantly lower for those with non-diethylstilbestrol-associated adenocarcinoma, 34%.⁴⁴ Vaginal melanoma, however, has much lower 5-year survival at 13%.⁴⁵ With regard to the primary tumour, tumours >4 cm, tumour ulceration and tumour infiltration into the rectovaginal septum are associated with significantly poorer prognosis compared with smaller exophytic tumours.²⁶ Tumour grade, however, had been shown to correlate with the development of distant metastases but not local disease.³⁴

MRI TECHNIQUE AND STAGING

MRI technique

MRI of the pelvis for vaginal cancer is similar to that for cervical cancer. The patient should be imaged supine with a torso- or pelvic-phased array coil. At some institutions, glucagon can be administered to decrease artefacts from bowel peristalsis. A partially filled bladder also helps displace bowel loops out of the pelvis. The utilization of a dry tampon or vaginal gel (Surgilube, Fougera; Melville, NY) provides better distension and visualization of the vagina, although not universally used.⁴⁶ For optimal tumour assessment, instillation of a dry tampon or vaginal gel into the vagina prior to the MR may be helpful (Figure 1).

Suggested guidelines from our institution, a dedicated cancer hospital, are as follows and summarized in Table 2. On a 1.5-T magnet, T₁ weighted images using a spin-echo pulse sequence with repetition time (TR) of 400–500 ms, echo time (TE) of 12 ms and k-space matrix size 256 × 192 in axial planes are obtained. Coronal T₂ weighted single shot fast spin echo images should include the kidneys to evaluate for hydronephrosis. T₂ weighted fast spin-echo images with a small field of view (24 cm) with thin sections (thickness, 5 mm; interslice gap, 0 mm) are acquired with TR 4000–6000 ms, TE 100–120 ms, in axial and sagittal planes. 3D dynamic gadolinium-enhanced images are acquired in a sagittal plane with a temporal resolution of 12 s, gradient echo TR 4.1 ms and TE 1.5 ms and matrix 320 × 200 with thin sections (thickness, 2 mm; no interslice gap, 1 signal average) over a period of 9 min.

Table 2.

MRI parameters for gynaecologic pelvis^a

Parameter	Cor SSFSE or haste	Ax T1 fast spin echo	Ax T2 fast spin echo	Sag T2 fast spin echo	3D Sag fat saturation dynamicb
Repetition time (ms)	2000	400–500	4000–6000	4000–6000	3.9–4.1
Echo time (ms)	102–140	10–12	100–120	100–120	1.5
Flip angle (°)	167	158	152	160	15
Field of view (mm)	340–440	240	240	240	240
Slice thickness (mm)	5	4–5	4–5	4–5	2–3
Acquisition matrix	256 × 160	256 × 192	384 × 224	512 × 256	320 × 192
Signal averages	1	2–3	3	3–4	1–2
Bandwidth (Hz per pixel)	698	178	200	199	410
Dimension (two dimensional/3D)	2D	2D	2D	2D	3D

3D, three dimensional; Ax, axial; Cor, coronal; SSFSE, single-shot fast spin-echo.

^aSuggested guidelines for MRI of the gynaecologic pelvis using a 1.5 T.

^bIncludes precontrast, followed by dynamic postintravenous contrast acquisitions.

On MRI, the three layers of the vaginal wall can be appreciated on T₂ weighted images, similar to the zonal anatomy of the uterus: the mucosa is hyperintense, the submucosal (consisting of collagen and elastic fibres) and muscularis layer hypointense, and the adventitia hyperintense due to a well-developed venous plexus (Figure 1).⁴⁷ With the use of vaginal gel, only two layers are evident, the hypointense muscularis and the hyperintense adventitia; the hyperintense mucosal layer is obscured by the hyperintense gel (Figure 1). The tumour itself is best assessed on T₂ weighted images, where it is of intermediate to high signal intensity relative to the submucosal and muscularis layer, which creates the hypointense peripheral band of the vaginal wall. Similar to cervical cancer, extension through the hypointense muscularis is important in staging. T₂ weighted images optimize tumour contrast from adjacent structures (bladder and rectal wall) and extension through the low-signal vaginal wall.⁴⁸

A fat-suppressed T₁ weighted sequence before and after administration of intravenous gadolinium can be utilized to assess tumour enhancement, particularly in evaluating recurrence and/or in patients who have received prior radiation. While no dedicated studies have been carried out on vaginal cancer, studies in cervical and endometrial cancer have shown that dynamic contrast enhancement may be helpful in differentiating tumour type (squamous vs adenocarcinoma), evaluating extent of tumour invasion/involvement, and distinguishing recurrence from fibrosis in treated patients.^49–51 Tumour recurrence, however, can often be detected on T₂ weighted images; typically, the tumour has a higher signal intensity compared with fibrosis, which has a low signal on the T₂ weighted images.⁵² Kinkel et al⁵¹ showed that the use of dynamic contrast-enhanced MR images in cervical cancer increased specificity, accuracy, positive and negative-predictive values from 22%, 68%, 70% and 57% to 67%, 83%, 86% and 86%, respectively. We believe that the addition of contrast administration and dynamic imaging may have a similar value in vaginal cancer, both for initial staging and follow-up. The use of diffusion-weighted imaging is promising and has shown potential for improving tumour detection in cervical cancer,^53,54 but its current role in vaginal cancer is unknown.

MR staging

Table 3 highlights MRI findings by stage and key imaging sequences.

Table 3.

MR staging of vaginal cancer

Stage	Description
Stage I	Preservation of low-signal vaginal wall on T2 weighted images (axiala)
Stage II	Disruption of low-signal vaginal wall on T2 weighted images (axiala); extension into the parametrial fat on T1 or T2 weighted images (axiala)
Stage III	Extension to pelvic sidewall; abnormally high signal of the musculature on T2 weighted images
Stage IV	Extension beyond the true pelvis or bladder and/or rectal involvement
IVA	–Extension beyond the pelvis or bladder or rectal invasion; disruption of the low-signal bladder or rectal wall on T2 weighted images or abnormal enhancement on contrast-enhanced T1 weighted images with fat suppression
IVB	–Distant organ metastases (lungs and liver)

^aMR image planes that may be the most helpful.

Stage I

For Stage I, tumour is limited to the vagina and has not extended into the paravaginal fat (Figure 2). On T₂ weighted images, the normal low T₂ signal of the vaginal wall (submucosal and muscularis) is intact (Figure 2b). This is analogous to the preservation of the T₂ hypointense fibromuscular stromal ring in cervical cancer, which has documented accuracy of 88–97% and a negative-predictive value of 94–100% on MRI.^55–57

Figure 2.

Stage I vaginal cancer. (a) A 62-year-old female with Stage I vaginal cancer. Axial T₂ weighted MR image shows a small mildly hyperintense mass confined to the right anterolateral vagina (arrow). (b) A 79-year-old female with Stage I vaginal cancer. Axial T₂ weighted MR image shows a larger Stage I tumour confined to the vagina with an intact low T₂ signal vaginal wall (muscularis) around the tumour (arrow). Biopsy confirmed squamous cell carcinoma.

Stage II

In Stage II, the low T₂ signal intensity of the vaginal wall is disrupted by the extension of tumour into the paravaginal fat (Figure 3). Similar to tumour detection in cervical cancer, axial images, perpendicular to the orientation of the vagina, are best for evaluating local spread beyond the vaginal wall. In cervical cancer, large or bulky tumours may result in the loss of the hypointense T₂ signal of the vaginal stroma and may mimic parametrial invasion; we suspect that this is also true and advise similar caution when assessing large or bulky vaginal tumours.⁵⁷

Figure 3.

A 57-year-old female with Stage II vaginal cancer. Axial T₂ weighted MR image shows the mass involving the paravaginal tissues (black arrow). The low T₂ signal vaginal muscularis is completely disrupted by tumour bilaterally. Biopsy confirmed squamous cell carcinoma.

Stage III

In Stage III, tumour extends locally to the pelvic sidewall (Figure 4a). Pelvic sidewall involvement is generally defined as tumour spread within 3 mm of the internal obturator, levator ani or piriformis muscles or iliac vessels.⁵⁸ On T₂ weighted images, one can observe abnormal signal with increased T₂ signal related to oedema or direct invasion of the tumour into the musculature itself (Figure 4b). Tethering of the musculature is also sometimes observed. In tumours with paravaginal and pelvic sidewall extension, evaluation of the coronal T₂ weighted images is particularly important to evaluate the kidneys for hydronephrosis.

Figure 4.

Vaginal cancer, pelvic sidewall involvement. (a) A 45-year-old female with Stage III vaginal cancer. Axial T₂ weighted MR image shows infiltrative mass at the vaginal fornix extending into the left pelvic sidewall (white arrow), involving the piriformis and the sciatic region. Biopsy confirmed poorly differentiated squamous cell carcinoma. (b) A 53-year-old female with Stage IV vaginal cancer. Axial T₂ weighted MR image shows infiltrative vaginal mass extending into the left pelvic sidewall (black arrow). Note the T₂ hyperintensity reflecting oedema within the obturator internus muscle (white arrow). Urethral involvement in this patient, however, established Stage IV disease.

Stage IV

For Stage IV, tumour extends beyond the true pelvis or may invade the bladder or rectum (Figures 5 and 6). Stage IV has been divided into Stage IVA, disease that has directly spread beyond the true pelvis and/or invaded the rectum or bladder, and Stage IVB, disease with distant metastases. MRI has high accuracy for detecting the bladder and rectal invasion, ranging from 96% to 99% with an excellent negative predictive value and interobserver agreement.^48,59–61 T₂ weighted images are important for evaluating loss of the fat planes and loss of normal low-signal intensity of the bladder or rectal wall (Figures 5 and 6).⁶² In addition to abnormal T₂ signal, contour abnormality such as irregularity and nodularity along the wall is also suspicious for invasion.⁴⁸ When suspecting invasion, evaluating an additional imaging plane is often helpful to verify the presence or absence of invasion (Figure 5b,c). Contrast-enhanced T₁ weighted images may improve accuracy. The presence of abnormal enhancement of the bladder or rectal wall or direct extension of soft tissue into the bladder or rectum is the sign of invasion on contrast-enhanced images.⁶³ In general, MRI can overstage bladder involvement as it is difficult to differentiate peritumoural oedema (bullous oedema) and inflammation from tumour infiltration; correlation with cystoscopy is suggested for confirmation in cases of suspected invasion.¹² Given the close proximity to the bladder and urethra anteriorly and the rectum posteriorly, invasion into the lower aspect of these structures may result in bladder outlet obstruction and urinary retention (Figure 5a) or rectal symptoms, respectively.

Figure 5.

Vaginal cancer, assessing bladder invasion. (a) A 60-year-old female with Stage IV vaginal cancer. Sagittal T₂ weighted MR image shows infiltrative vaginal mass involving the urethra and bladder base (arrow). Note the markedly distended bladder (asterisk) related to bladder outlet obstruction. Biopsy confirmed squamous cell carcinoma. (b) An 87-year-old female with vaginal cancer, pitfall for bladder invasion. Sagittal T₂ weighted MR image demonstrates tumour bulging into the posterior aspect of the bladder (arrow). This can mimic bladder invasion and is a common pitfall. (c) Axial T₂ weighted MR image in the same patient in (b) shows no bladder invasion and preserved low T₂ signal of the bladder wall (arrow). The tumour indents the posterior bladder wall but does not invade, making this Stage II rather than Stage IV; this was confirmed by cystoscopy.

Figure 6.

A 57-year-old female with Stage IV vaginal cancer invading the rectum. Axial T₂ weighted MR image shows a T₂ hyperintense vaginal mass invading the anterior rectal wall (arrow) and involving the left puborectalis muscle (asterisk).

TREATMENT

Treatment of vaginal cancer is guided by the FIGO stage and is summarized in Table 4. Because vaginal cancer is rare, there is much discussion and controversy over preferred treatment. Many guidelines are in fact extrapolated from treatments of cervical cancer and individualized to many centres. If diagnosed and staged early, both surgical resection and radiation can be curative in vaginal cancer.^31,64 In the majority of patients and especially more advanced stages, radiation plays a central role in vaginal cancer treatment, consisting of external beam radiation and brachytherapy.³¹ Radiation is advantageous due to preservation of the vagina.^31,65 External beam radiation to the pelvis utilizes CT simulation for 3D conformal treatment planning for more effective tumour dose. Inclusion of external, iliac and obturator nodes in the radiation field is standard. In addition, inguinal nodes are included in the radiation field for distal vaginal tumours, and perirectal and presacral nodes for tumours of the superior posterior vagina or those involving the rectovaginal septum. Cylinder brachytherapy and interstitial implants are reserved for smaller volume or residual disease. MRI is often used to assess response after external beam radiation or to assess and localize initial tumour volume prior to brachytherapy, guide brachytherapy placement and evaluate subsequent response. We briefly describe and summarize key treatment strategies by stages. Figure 7 documents imaging during the course of treatment for a patient with Stage II vaginal cancer.

Table 4.

Treatment of vaginal cancer by International Federation of Gynecology and Obstetrics stage

Stage	Tumour extent	Treatment
I	Confined to vagina	EBRT with BT. Consider surgery for small (<2 cm), minimally invasive exophytic tumours
II	Paravaginal tissues but not pelvic wall	Combination of BT and EBRT
III	Pelvic wall	EBRT with or without brachytherapy
IVA	Extension beyond true pelvis and/or invasion of bladder or rectum	EBRT with or without brachytherapy
IVB	Distant metastasis	Chemotherapy with palliative EBRT as indicated

BT, brachytherapy; EBRT, external beam radiation therapy.

Figure 7.

Imaging at different stages of treatment for a 71-year-old female with Stage II vaginal cancer. (a) Axial T₂ weighted MR image shows tumour extending into the paravaginal space with loss of the normal hypointense T₂ vaginal wall (arrow). (b, c) Axial and sagittal images from three-dimensional CT simulation treatment plan show targeting of the primary vaginal tumour and iliac and obturator nodal chains for external beam radiation. (d) Axial T₂ weighted MR image after external beam radiation shows marked decrease in initial vaginal tumour volume (arrow). (e, f) Localized radiation with brachytherapy. Frontal pelvic radiograph and axial T₂ weighted MR image show placement of brachytherapy cylinder [asterisk in (f)] with radiation needles into the vagina for administration of localized therapy. Note the residual tumour of the left lateral aspect of the vagina [white arrowheads in (f)]. (g) Axial T₂ weighted MR image following brachytherapy shows continued decrease and near resolution of vaginal tumour (arrow).

Stage I

Radiation therapy is the most common treatment for Stage I vaginal cancer, but surgery may play a role in very early and minimally invasive lesions.⁶⁵ Typically, combined brachytherapy and external beam radiation therapy (EBRT) are used although some authors report favourable outcomes with brachytherapy alone.^31,66 For tumours of the lower vagina, intracavitary and EBRT are preferred. In tumours of the upper vagina, external beam with brachytherapy or surgery (partial or radical vaginectomy, radical hysterectomy and pelvic lymph node dissection) can be considered. Adjuvant radiation (external beam) can treat residual tumour deposits in patients with positive margins or lymph node-positive disease. Due to the close proximity of critical structures and risk of complications, larger tumours are rarely suitable for surgery.⁶⁷

Stage II

Radiotherapy is the most common treatment for Stage II disease. Standard radiation treatment consists of a combination of EBRT and brachytherapy (Figure 7).⁶⁶ Radical surgery (radical vaginectomy or pelvic exenteration) with or without radiotherapy is also an option but is highly morbid so radiation therapy is generally preferred.^18,68,69 Concurrent chemotherapy is often recommended as a radiosensitizer for Stage II–IVA vaginal cancer, based on randomized data in cervical cancer, and high incidence of distant metastases reported in one of the larger studies on vaginal cancer by Perez et al,³⁴ 30% in patients with Stage II and 50% in Stage III.

Stages III/IV

For Stage III disease, EBRT alone or in combination with brachytherapy is the treatment of choice. Combined chemoradiation has shown high clinical and metabolic responses in females with advanced (Stages III and IV) vaginal cancer.⁷⁰ Treatment for Stage IVA disease is the same as for Stage III, EBRT with or without brachytherapy.^{31,36,40,66,71} For patients with Stage IVB disease, chemotherapy with palliative radiation is generally recommended.^20,72,73

POST-TREATMENT MRI: RECURRENCE AND COMPLICATIONS

Locoregional recurrences in vaginal cancer are the most common, seen in 23–26% of patients at 5 years and accounting for 68% of relapses in early-stage (Stage I/II) disease and 83% in later stage (Stages III/IV).^31,40 Most local recurrences are seen within the first few years, almost 80% by 2 years and 90% by 5 years.^31,40 Staging has been shown to be the principal predictive variable for recurrence, reported at 24% for Stage I, 31–32% for Stage II, 53% for Stage III and 73–83% for Stage IV.⁴⁰ There has been conflicting evidence for lesion location, grade, and HPV status as predictors of recurrence.⁷⁴ A study by Tarraza et al⁷⁵ (n = 41), however, found that recurrence site varied with location of the initial tumour, upper vaginal lesions more commonly recurring locally, and lower vaginal lesions more commonly associated with pelvic sidewall or even distant recurrence. A larger study by Chyle et al⁴⁰ (n = 301) found that both locoregional and metastatic recurrence were more common in larger lesions (>5 cm), lower vaginal (middle and distal third of the vagina) and posterior wall lesions. In patients with recurrence, survival is particularly poor, overall 12% at 5 years and again varies according to stages: 12–18% for Stages I/II and 0–3% for Stages III/IV.⁴⁰ Patients with local recurrence generally do better than those with regional or distant spread, 20% 5-year survival compared with 4%, respectively.⁴⁰

MRI is useful in staging patients with vaginal recurrence, with reported accuracy of 82–95%.^11,76 Following pelvic irradiation, the vaginal wall shows T₂ hyperintense signal during the first 6 months due to mucosal and intramuscular oedema, making detection of residual or recurrent disease difficult.⁶² Decrease in tumour size, though, is easily assessed. In these patients, contrast-enhanced 3D dynamic sequences are particularly helpful (Figure 8). Scar or treated tumour will be hypointense on T₂ and will not show early avid enhancement on contrast-enhanced T₁ weighted imaging. Tumour, however, will be hyperintense on T₂ and enhance early and avidly (Figure 8).⁷⁷ When recurrence is suspected more than 6 months after treatment, MRI readily differentiates between scar tissue and cancer; by this point, radiation-induced oedema should have resolved. A previous study by Ebner et al⁵² suggested that distinction between fibrosis and recurrent disease can be made solely on T₂ weighted imaging at 12–18 months after treatment (Figures 8 and 9). ¹⁸F-FDG-PET/CT can also be helpful in assessing for recurrent disease, but the extent of local tumour infiltration and tumour volume will be better assessed on MRI.

Figure 8.

A 69-year-old female, status after partial vaginectomy with recurrent tumour 1 year later. (a) Sagittal T₂ weighted MR image shows diffuse thickening of the residual vagina (arrow). (b) Sagittal fat-suppressed T₁ weighted contrast-enhanced MR image shows diffuse enhancement compatible with locally recurrent tumour (arrow). Note that the uterus is surgically absent.

Figure 9.

A 47-year-old female with a history of vaginal intraepithelial neoplasia, status after upper vaginectomy with recurrent vaginal mass 15 months later. (a) Sagittal T₂ weighted MR image shows a mass involving the vaginal cuff and upper half of the remaining vagina (arrow). Biopsy confirmed squamous cell carcinoma. (b) Sagittal T₂ weighted MR image following treatment with chemoradiation shows resolution of the vaginal mass. Mild residual very low T₂ signal (arrow) is compatible with fibrosis.

Reported common clinical complications include radiation-induced bladder, rectal and vaginal toxicity; the latter is proportional to the extent of vaginal invasion and FIGO stage.¹⁶ Increasing stage, tumour size and total radiation dose predict higher likelihood of complications.³⁶ For instance, the 10-year complication incidence for Stages I/II is reported at 8–14% and for Stages III/IV 23–40%.⁴⁰ Complications most commonly present within 5 years of treatment but can be seen up to 20 years later.⁴⁰

On imaging, complications after radiation are common, reported in up to 30% of patients with rectovaginal and vesicovaginal fistulas (Figure 10) seen in 21%.²⁹ Cystitis, proctitis, bowel stricture and perforation, pelvic bone osteonecrosis and stress fractures also occur. Various imaging modalities can be utilized to assess for complications, including MRI. MRI is particularly helpful in depicting and delineating fistulas, with reported accuracy of 91% in vaginal fistulas.⁷⁸ The appearance of fistulas on MRI is best assessed on T₂ weighted images, where a fluid-filled fistula may be seen as a tract of high-signal intensity and an air-filled tract of low-signal intensity. The sagittal plane can be used to optimize localization of the fistula, assessing for disruption or discontinuity of the vaginal, bladder or rectal wall (Figure 10).^49,79 In addition to detecting complications such as fistulae in these patients, MRI also readily demonstrates the presence of residual or recurrent tumour, as we have previously described.

Figure 10.

A 55-year-old female with vaginal cancer complicated by radiation-induced vesicovaginal fistula. Sagittal T₂ weighted MR image shows communication between the lower vagina and bladder neck/urethra (arrow).

CONCLUSION

Primary vaginal cancer is a rare, yet important, gynaecologic malignancy. Knowledge and familiarity with the MRI features in primary vaginal cancer is useful in diagnosis, local staging, treatment planning and assessment of complications.