Serum C-reactive protein/albumin ratio as a prognostic marker in oral squamous cell carcinoma

Abstract

Background and Aim:

Systemic inflammation in response to oral squamous cell carcinoma (OSCC) has been known to be a detrimental factor for the prognosis of the patients. Inflammation-based predictive biomarkers, like levels of serum C-reactive protein (CRP) and albumin, have been associated with rise and decline, respectively, with the advancement of malignancy. A ratio of their serum levels is being recently advocated to be a better prognostic predictor. We evaluated the association of the ratio of serum CRP and albumin with the clinical stage and histological grade of OSCC.

Methods:

Thirty-five histopathologically confirmed patients of OSCC were included in the study, and the serum levels of CRP, albumin, and ratio of the serum CRP and albumin levels were measured in patients with different clinical stages and histological grades of the OSCC.

Results:

Serum CRP levels showed a progressive statistically significant increase with the advancement of the clinical stage from stage I to stage IV and histological grade of OSCC. The serum levels of albumin exhibited a progressive decline, though statistically insignificant, with the advancement of clinical stage and histological grade of OSCC. The mean value of the ratio of serum CRP and albumin progressively increased with the clinical stage and histological grade of OSCC. Pearson’s correlation analysis revealed a significant correlation of the ratio of serum CRP and albumin with the clinical stage of OSCC, although not with the histological grade of OSCC.

Conclusion:

The ratio of serum CRP and albumin can be employed as a serological marker for the prognosis of OSCC and may aid in the postoperative monitoring of the patients with OSCC.

INTRODUCTION

Oral cancer is the sixth most common cancer, and India shares a burden of one-third of the oral cancer cases globally. Annually, around 77,000 new cases and 52,000 deaths due to oral cancer are reported in India, with around 70% of the cases being reported in the advanced stages (stages III–IV, American Joint Committee on Cancer). Detection of the cancer cases at advanced stages reduces the chances of cure, allowing a survival rate of around 20% only.[1,2]

Oral squamous cell carcinoma (OSCC) significantly contributes to the burden of oral cancer, with 84%–97% of the oral cancer cases being diagnosed as OSCC.[3] Despite advancements in the diagnostic and therapeutic approaches, the oncologic outcomes are greatly influenced by many prognostic factors, like the age of the patients, tumour diameter and depth, residual carcinoma at the surgical margins, perineural and vascular invasion, number of lymph nodes with metastasis, etc.[4]

In addition to these factors, several other histopathological and behavioural parameters are known to influence the therapeutic outcomes of OSCC. The invasive tumour front (ITF) has been recognized as a critical determinant of tumour aggressiveness and metastatic potential. The degree of stromal eosinophilia has been variably correlated with both improved and worsened prognosis, depending on its intensity. Tobacco use and allied habits remain important predictors of recurrence and second primary tumours because of their role in field cancerization. Furthermore, the pattern of invasion (POI) of OSCC is a well-established independent predictor of cervical lymph node metastasis and overall survival.[4]

Additionally, cancer-associated systemic inflammatory response, reflecting both the disease activity and the host immune response, largely influences the oncologic outcomes and is thereby readily substantiating its utility as a prognostic determinant in cancer. The measures of this inflammatory response, like the C-reactive protein, albumin, and white blood cell counts, have been exploited for their prognostic values in various human cancers.[5,6,7,8,9]

For decades, the TNM staging system has been the cornerstone for prognostic stratification of OSCC. The recently released 8^th edition of the American Joint Committee on Cancer (AJCC) staging manual introduced important refinements, including depth of invasion and extranodal extension, thereby improving prognostic accuracy.[10,11,12,13] Although the framework thoroughly considers the clinical and pathological characteristics of OSCC, host factors, like the systemic inflammatory response, remain outside its consideration for prognostication. Moreover, the histopathological characteristics incorporated in the framework are usually obtained postoperatively.[14] Thus, any prognostic determinant that can be obtained before surgery might aid better in the management and prognostication of OSCC.

Serum C-reactive protein (CRP) is a cheap and simple biomarker for the diagnosis of acute and chronic inflammatory conditions. The decade-long emphasis on the linkage of malignancies and inflammation ideates the use of estimation of serum CRP in the diagnostic or prognostic procedures of malignancies. Recent studies have consistently demonstrated that elevated serum CRP levels are associated with poor survival in breast carcinoma, colorectal cancer, lung cancer, pancreatic cancer, and oesophageal squamous cell carcinoma, among others, and have been proposed to be used for post-therapy monitoring.[15]

However, serum levels of albumin, a protein with antioxidant and anti-inflammatory properties, bear a negative correlation with cancer-related mortality. Low levels of the protein have already been serving as prognostic indicators for conditions of the cardiovascular system, renal insufficiencies, hepatic lesions, and COVID-19.[16]

We attempted to appraise a correlation between the ratio of serum levels of CRP and albumin and the clinical and histological grades of OSCC. A correlation, if any discovered, shall become an aid in the diagnosis and prognosis of the disease, or may even be exploited to devise a therapeutic strategy for the disease.

MATERIALS AND METHODS

The study was conducted at the Department of Oral Pathology, in collaboration with the Department of Biochemistry at our institute, and was approved by the Institutional Ethics Committee. The study was designed as a cross-sectional descriptive study comprising 35 patients with histologically confirmed OSCC, who had not received or were receiving any treatment for the malignancy.

Patients with any other inflammatory or neoplastic disease were excluded from the study. In addition, individuals with systemic debilitating conditions known to independently alter serum CRP or albumin levels—such as uncontrolled hypertension, type 2 diabetes mellitus, cardiovascular disorders (e.g. ischemic heart disease, heart failure), chronic kidney or liver disease, asthma, chronic obstructive pulmonary disease, autoimmune disorders, or any active systemic infection—were also excluded. Patients on corticosteroid or immunosuppressive therapy were not considered for inclusion. This strict selection ensured that the study population represented OSCC patients without systemic confounders that could bias the interpretation of the CRP/albumin ratio.

After obtaining informed consent, all eligible patients were examined thoroughly and evaluated for the clinical stage and histopathological grade of the disease. Clinical staging was performed according to the 9^th version of the AJCC (American Joint Committee on Cancer) Cancer Staging System.[17]

Under strict aseptic conditions, incisional or excisional biopsy tissue specimens were obtained and processed for histological grading of the tumours according to the grading system proposed by Anneroth G et al.[18]

Lastly, 5 ml of fasting venous blood samples was collected from each patient, allowed to clot at room temperature for about one to two hours, and then centrifuged at 3,000 rpm for 10 min to separate the serum. Levels of serum CRP and albumin were estimated using the Robonik®-prietest TOUCH™ biochemical analyser, and a ratio of serum CRP to albumin was calculated for each patient.

Statistical analysis of the generated data was performed using the Statistical Package for the Social Sciences (SPSS version 20.0; Chicago Inc., USA). Quantitative variables were expressed as means and qualitative variables as proportions for statistical comparisons.

RESULTS

The age of the patients included in the study ranged from 29 years to 80 years, with a mean age of 55.97 ± 12.08 years. The peak incidence of OSCC was seen in the seventh decade, followed by 40% of the patients in the fifth decade and 20% in the sixth decade of life. The incidence was minimum in the second, third, and eighth decades of life. Of the 35 patients with OSCC, 23 patients were male, with a male-to-female ratio of 1.8:1 [Table 1].

Table 1.

Demographic distribution of the study patients

n	Age group (years)							Sex
	20–29	30–39	40–49	50–59	60–69	70–79	80–89	Male	Female
	1	2	8	7	14	2	1	23	12

Among the included OSCC patients, maximum patients (62.85%) showed stage III disease according to the ninth version of the AJCC Cancer Staging System, followed by the number of patients with stage II, stage I, and stage IV disease. Histopathologically, of the included 35 patients, 80% of the patients had a grade II tumour according to grading system by Anneroth et al.,[19] followed by the number of patients with grade I. None of the patients had a grade III tumour [Table 2].

Table 2.

Demographic distribution of the study patients according to the clinical stage and histopathological grade of OSCC

n	Clinical stage				Histopathological grade
	I	II	III	IV	I	II	III
	4	7	22	2	7	28	0

OSCC=Oral squamous cell carcinoma

The mean serum levels of CRP showed a progressive rise with the clinical stage and histopathological grade of the disease, with a mean serum CRP values of 3.43 mg/dL in patients with stage I OSCC and 37.77 mg/dL in those with stage IV OSCC, and 8.27 mg/dL in patients with grade I tumours and 13.72 mg/dL in those with grade II tumours, the difference in the mean values across all the stages and grades of OSCC being statistically significant. On the contrary, the serum levels of albumin showed a fall with the progression of the stage and grade of OSCC, with a mean serum albumin value of 4.5 g/dL in patients with stage I OSCC and 3.45 g/dL in those with stage IV OSCC and 4.46 g/dL in patients with grade I tumours and 3.87 g/dL in those with grade II tumours, the difference in the values across the stages and grades of OSCC, however, not being statistically significant [Table 3].

Table 3.

Mean serum levels of CRP and albumin and mean values of serum CRP to albumin ratio across all the clinical stages and histopathological grades in the study patients with OSCC

	Clinical stage				Histopathological grade
	I (n=4)	II (n=7)	III (n=22)	IV (n=2)	I (n=7)	II (n=28)	III (n=0)
Mean serum levels of CRP (mean mg/dL)	3.43±1.33	5.00±4.90	14.45±13.81	37.77±5.90	8.27±6.51	13.72±16.68
t-test					P=0.05*
ANOVA	P=0.005**
Mean serum levels of albumin (mean g/dL)	4.50±0.38	4.25±0.81	3.86±0.80	3.45±0.35	4.46±0.68	3.87±0.76
t-test					P=0.84***
ANOVA	P=0.25***
Mean value of serum CRP to albumin ratio	0.76±0.27	1.20±0.96	3.77±3.88	10.91±0.59	1.88±1.41	3.68±4.17
t-test					P=0.27***
ANOVA	f=5.665, P=0.003**
Post hoc Tukey test	P=0.996
	P=0.334
	P=0.005**
	P=0.279
	P=0.004**
	P=0.026*

*Statistically significant. **Highly statistically significant. ***Statistically insignificant. CRP=C-reactive protein, OSCC=oral squamous cell carcinoma, ANOVA=analysis of variance

The ratio of the serum levels of CRP and albumin was calculated for each OSCC patient, and the mean values were statistically compared using the ANOVA across the different clinical stages and histopathological grades of the disease. The mean values of the ratio significantly increased with the clinical progression of the disease, with the value being 0.76 in patients with stage I OSCC and 10.91 in those with stage IV disease, with the mean value of the ratio in patients with stage IV OSCC being significantly higher than in those with stages I, II, or III OSCC. Likewise, the mean values of the ration of the serum CRP and albumin increased with the histopathological grade of the disease, with the value being 1.88 in patients with grade I tumours and 3.68 in those with grade II tumours, however, the difference not being statistically significant [Table 3].

DISCUSSION

Our study exhibited a progressive rise in the serum levels of CRP and fall in the serum levels of albumin with the advancement of the clinical stage and histopathological grade of OSCC. The least mean value of the serum CRP was recorded as 3.43 mg/dL in patients with OSCC in the clinical stage I and the highest mean value of the serum CRP as 37.77 mg/dL in those with clinical stage IV OSCC. Vankadara S et al.[20] compared the serum CRP levels among healthy individuals and patients diagnosed with oral potentially malignant disorders (OPMDs) and OSCC. The mean serum levels of CRP in healthy individuals in their study (3.88 mg/dL) were close to the values that were noted in patients with clinical stage I OSCC in our study. They further added that there was an elevation in the mean serum levels of CRP in patients with OPMDs and OSCC, with the mean serum levels reported in OSCC (31.72 mg/dL) being closer to the mean serum levels of CRP in patients with clinical stage IV OSCC in our study.

However, Chen HH et al.,[21] who had also included patients diagnosed with leucoplakia along with those with OSCC in their study on assessment of serum CRP levels, did not report a significant association between the elevated serum CRP levels and diabetes, liver cirrhosis, smoking, alcohol consumption, or areca quid chewing in patients with oral leucoplakia. Their results were yet supportive to those of our study, with an exhibition of elevated serum CRP levels being significantly associated with the stage of tumour, bone invasion, lymph node metastasis, and lymph-node extracapsular spread. Furthermore, they found that higher serum CRP levels were significantly associated with a poorer disease-free survival and overall survival. Since then, serum CRP level is being investigated for its potential as an indicator of prognosis in patients with OSCC.

Meanwhile, there ensued a debate over the other probable concomitant causes for the elevation of serum CRP levels in patients with OSCC, like pulmonary or other infections. Therefore, Tai SF et al.[22] included a large number of patients with OSCC (343 cases) to clear the air and found that 83% of the patients with OSCC had elevated serum CRP levels at both the diagnosis and the day of surgery. They further attempted to draw a connection between the preoperative serum CRP levels, stage of OSCC, and prognosis and found a significant relationship between raised serum CRP and the stage of the tumour, tumour depth and invasiveness, lymph node involvement at an elevation of the serum CRP levels of ≥5.0 mg/L. Additionally, they stated that all these correlations were more pronounced in OSCCs of buccal mucosa than the tumours of other intraoral sites, along with an added correlation of the elevated serum CRP levels with disease-free survival and overall survival in patients with buccal mucosa OSCCs than in those with tumours at other sites.

Likewise, Acharya S et al.[23] reported a significantly higher serum CRP levels in 70% of the 60 OSCC patients than in the healthy individuals and a positive correlation of raised serum CRP levels with the lymph node involvement clinically and histologically. They further proposed a cut-off level of serum CRP of 8.65 mg/l as predictive of lymph node involvement, with a sensitivity and specificity of 0.767, thus crowning the serum CRP levels as an additional prognostic parameter in patients with OSCC. Later, Zhang Y and Gu D through their study on 208 OSCC patients reported that patients with serum CRP levels of ≤11.3 mg/L had better survival than those with serum CRP levels more than the value. They also announced that serum CRP levels >11.3 mg/L in patients with any stage of lymph node involvement was an ominous sign for disease-free and overall survival in the patients.[24]

The fall in the serum levels of albumin in OSCC patients in our study with the advancement of clinical stage and histological grade may be an indication of deranged nutritional status due to inflammatory reactions towards the disease.[25] Such low serum levels of albumin, both preoperatively and postoperatively, have been attributed to postoperative wound complications and survival in OSCC patients and subjected to surgery.[26,27,28,29] Lim WS et al.[29] analysed the effects of low preoperative serum albumin levels in 338 patients with head and neck squamous cell carcinoma undergoing surgery, radiotherapy, and/or chemotherapy and reported that the pretreatment serum albumin level was independent predictor of disease-free survival, disease-specific survival, and overall survival with a six-fold higher risk of tumour progression and disease-specific and overall mortality than the patients with normal serum albumin levels pre- and postoperatively. Recently, Tang Q et al.[16] in an extensive cohort study on the association of serum albumin levels with prognosis in OSCC patients demonstrated that, regardless of the OSCC aggressiveness and other confounding factors, the patients with serum albumin levels ≤4.2 g/dl had poorer survival than those with higher levels.

The ratio of serum CRP and albumin significantly increased with the progression of the clinical stage of OSCC. The increase was also seen to be associated with the progression of histological grade of OSCC, however, the increase being statistically insignificant. Yamagata K et al.,[30] through their study examining the prognostic value of the serum CRP to albumin ratio in patients with OSCC, proposed a cut-off value for the ratio to be 0.032 to predict overall survival in the patients with 59.3% sensitivity and 75.3% specificity. Keinänen A et al.[31] evaluated the role of oral health and factors that may influence the preoperative serum CRP and albumin levels and thereby the ration of serum CRP and albumin levels. They suggested that heavy alcohol use and Charlson comorbidity index (CCI) are the only independent variables for the increase in the ratio, out of all the other variables. Additionally, they reported a significant association between a high ratio of serum CRP and albumin levels and postoperative infections. They further commented that the ratio is a better assessor of early prognosis in the OSCC patients.

Impact of systemic comorbidities on CRP–Albumin Ratio

It is well established that CRP and albumin levels can be influenced by systemic conditions such as type 2 diabetes mellitus, cardiovascular diseases, chronic kidney or liver disease, and autoimmune or infectious disorders. Elevated CRP levels are frequently reported as predictors of cardiovascular events and poor glycaemic control in diabetes, whereas hypoalbuminemia is common in chronic illness and malnutrition. These alterations could potentially confound the interpretation of the CRP/albumin ratio in OSCC patients. In our study, this confounding effect was minimized by excluding patients with known systemic comorbidities or active infections at the time of blood sampling, thereby ensuring that the alterations observed in CRP and albumin levels were primarily tumour- and host-response related. Nevertheless, in clinical practice, OSCC patients often present with comorbidities, which may necessitate adjustment of biomarker cut-off values or multivariate models incorporating comorbidity indices to improve prognostic accuracy in future studies.

The study had certain limitations like the large heterogeneity of the cases of OSCC included in the study. Moreover, since the study was conducted at a tertiary referral centre, patients possibly reported late with advanced stage of the disease. A long-term follow-up and thereby the association of the serum CRP and albumin ratio with the outcomes of the treatment regimens, and the association with different treatment regimens was not performed.

CONCLUSION

Research has always been focused on the discovery of biomarkers for diagnosis and prognosis of patients suffering from OSCC. The mean value of ratio of serum CRP and albumin increased with the progression of clinical stage and histological grade of the OSCC. The pre- and postoperative values of the ratio may thus prove to be rapid, easy, and cost-effective predictor of prognosis and aid in monitoring the patients with OSCC.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.