Table 1.
Classification systems to predict tumour resectability
| Study group | Classification | Definitions | Outcomes | |
|---|---|---|---|---|
| Mayo Clinic[36] | Symptoms | S0 | Asymptomatic | Patients who were pain-free had better survival |
| S1 | Symptomatic without pain | |||
| S2 | Symptomatic with pain | |||
| Degree and site of Fixation | F0 | No fixation | More points of fixation resulted in more complications and worse survival | |
| F1 | Fixation to 1 point | |||
| F2 | Fixation to 2 points | |||
| F3 | Fixation to >2 points | |||
| Yamada[37] | Pattern of pelvic fixation | Localized | Invasion to adjacent pelvic organs or tissue | 5-year survival of 38% |
| Sacral invasive | Invasion to lower sacrum (S3, S4, S5), coccyx, periosteum | 5-year survival of 10% | ||
| Lateral invasive | Invasion to sciatic nerve, greater sciatic foramen, lateral pelvic wall, upper sacrum (S1, S2) | 5-year survival of 0% | ||
| Wanebo[38] | Five stages | TR1 | Limited invasion of the muscularis | |
| TR2 | Full thickness penetration of muscularis propria | |||
| TR3 | Anastomotic recurrences with full thickness penetration beyond the bowel wall and into the perirectal soft tissue | |||
| TR4 | Invasion into adjacent organs without fixation | |||
| TR5 | Invasion of the bony ligamentous pelvis including sacrum, low pelvic/side walls, or sacrotuberous/ischial ligaments | |||
| MSK[40–42] | Anatomic region involved | Axial | Anastomotic, mesorectal, perirectal soft tissue, perineum (APER) | Axial only recurrence has 90% likelihood of R0; lateral recurrence is associated with 36% likelihood of R0 |
| Anterior | Genitourinary tract | |||
| Posterior | Sacrum and presacral fascia | |||
| Lateral | Soft tissues of the pelvic sidewall and lateral bony pelvis | |||
| RMH[43] | MRI; Planes of dissection | Central | Rectum or neo-rectum, intra-luminal recurrence, peri-rectal fat or mesorectum, extra-luminal recurrence | MRI diagnosis of tumour invasion within the lateral, posterior or in more than 2 compartments was associated with reduced disease-free survival |
| PR | Rectovesical pouch or recto-uterine pouch of Douglas | |||
| AA PR | Ureters and iliac vessels above the peritoneal reflection, sigmoid colon, small bowel and lateral side wall fascia | |||
| AB PR | Genitourinary system | |||
| Lateral | Ureters, external and internal iliac vessels, lateral pelvic lymph nodes, sciatic nerve, sciatic notch, S1 and S2 nerve roots, piriformis or obturator internus muscle | |||
| Posterior | Coccyx, presacral fascia, retro-sacral space, sacrum up to the upper level of S1 | |||
| Inferior | Levator ani muscles, external sphincter complex, perineal scar (APER), ischio-anal fossa |