Abstract
Objective: To determine whether serum squamous cell carcinoma antigen (SCC-Ag) is predictive of treatment response in patients with squamous cell cervical carcinoma (SCC) undergoing chemoradiation therapy, and to establish the mean normal serum SCC-Ag level in age-matched, apparently healthy female controls.
Methods: Patients with histologically confirmed cervical SCC scheduled for concurrent chemoradiation were recruited (75 cases, alongside 75 age-matched apparently healthy controls, N = 150). Blood samples were collected before treatment and 6 weeks post-external beam radiotherapy to assess serum SCC-Ag levels, which were correlated with tumor stage and grade. Age-matched apparently healthy controls were also phlebotomized at baseline and 12 weeks later to determine normal SCC-Ag levels. Serum SCC-Ag was analyzed using Alinity i SCC reagent and analyzer (Abbott Laboratories, Chicago, IL, USA). The manufacturer's reference value for SCC-Ag is ≤1.5 ng/ml. Treatment response was assessed via pre- and post-treatment abdominopelvic computed tomography scans and classified as either complete or partial response. Data analysis was performed using SPSS v22.0, and logistic regression was used to evaluate predictors of treatment response. A P value <0.05 was considered statistically significant.
Results: The mean age was 55.1 ± 11.6 years for cases and 55.5 ± 11.4 years for controls. Among cervical cancer patients, the median pre-treatment SCC-Ag level was 7.4 ng/ml, and post-treatment was 1.2 ng/ml, both significantly higher than in controls (0.4 ng/ml and 0.5 ng/ml, respectively). Vaginal bleeding was the most common symptom (94.7%), and 68% presented with locally advanced disease. SCC histology was confirmed in 94.7% of cases, and 61% showed either complete or partial treatment response. Median SCC-Ag levels were significantly associated with disease stage (P<0.001) but not with tumor grade (P=0.159). Logistic regression identified tumor size as a significant predictor of treatment response, while pre-treatment SCC-Ag and SCC-Ag reduction rate were not.
Conclusion: Serum SCC-Ag levels were normal among all healthy controls and some patients with prior treatment. SCC-Ag correlated with disease stage but was not predictive of treatment response in patients undergoing chemoradiation. Tumor size was the only significant predictor of treatment response.
Cervical cancer is the leading gynecologic cancer in females in Nigeria and worldwide. Globally, there were 341,831 deaths from 604,127 new cases of cervical cancer recorded in 2020.1] In Nigeria, according to Globocan 2020, cervical cancer ranked as the third most common cancer, (both in terms of incidence and mortality), in both men and women after breast and prostate cancer.2 The most common histologic type is squamous cell carcinoma (SCC), accounting for three-quarters of all cervical cancers.3
Most patients in Nigeria present late, with locally advanced disease.4 Concurrent chemoradiation therapy and brachytherapy remain the standard of care for locally advanced and some early stage cancers.5 The standard guidelines in use in clinical practice, for the management of cervical cancer, like National Comprehensive Cancer Network (NCCN) and American Society of Clinical Oncology (ASCO), do not have tumor markers for use in monitoring progress while on treatment or post treatment, largely because use of tumor markers in cervical cancer is still investigational.6 Treatment monitoring tools are limited; hence, treatment response is usually assessed by physical examination and repeat imaging of the pelvis, usually about 6–12 weeks post chemoradiation therapy. Assessing serum levels of SCC antigen has proven efficacious in monitoring treatment response in cervical cancer, though it is not practiced locally in Nigeria and not present in international guidelines.7
SCC-Ag is a 48,000 Dalton (kDa) glycoprotein present in normal cervical tissue but with higher expression in malignant cervical tissue. It is readily detected via serum radioimmunoassay and is useful for monitoring disease in cervical cancer.8 Wang et al.9 found pre-treatment serum levels of SCC-Ag in cervical cancer patients were related to clinical stages, lymphovascular space invasion, and myometrial invasion. There was paucity of data on SCC-Ag use in low-to-middle-income countries as a prognostic index for cervical cancer.10 Ahmed et al.,10 in a study done in Egypt using cervical cancer tissue specimen, showed good discrimination between early and late stage disease and well differentiated and poorly differentiated histologic grades using SCC-Ag. SCC-Ag has been found to be elevated in sera and tissue extracts obtained from cervical cancer patients.10
The knowledge gained from this study, carried out among Nigerians, in sub-Saharan Africa, focused on determining if SCC-Ag is predictive of treatment response, the association between pre-treatment serum SCC-Ag levels and the disease stage and grade in patients with SCC on chemoradiation therapy, and the mean normal SCC-Ag level in female age-matched apparently healthy controls.
Methods
Data and Population
This was a case–control study conducted in two tertiary health centers in Nigeria. Approval was granted by the Health Research and Ethics Committees of the respective institutions - Lagos University Teaching Hospital (LUTH) and the National Hospital Abuja (NHA). Data collection was between July 2021 and August 2022.
Prior to recruitment of eligible participants, a written informed consent was obtained from both cases and controls. Thereafter, information was collected from both cases and controls using a clinician-administered questionnaire and from case notes using the proforma designed for the study. The patients (cases) were staged clinically using the FIGO staging. Treatment response was assessed from routine post-treatment imaging by comparing with routine pre-treatment imaging.
Research participants comprised 75 patients with histologically confirmed SCC of cervix stages 1B2 to IV on chemoradiation treatment at the Department of Radiotherapy in the NSIA-LUTH cancer center (NLCC) and the NHA. The control group consisted of 75 apparently healthy, age-matched female staff members of NLCC and LUTH, giving a total sample size of 150 participants. In terms of sample size calculation, a consecutive sampling of patients who met the eligibility criteria and willingly consented to participate were included in both arms of the study. Using the appropriate formula for studies comparing mean values of variables in differing groups such as cases and controls and adjusting for a non-compliance of 18%, a sample size of 75 cases was arrived at. Each case was age-matched to a control, yielding a total sample size of 150.
The inclusion criteria (cases) were age ≥ 18 years, cervical carcinoma with squamous cell component, stages 1B2 to IV cervical cancer on chemoradiation for the first time, and ECOG performance status of 0–3. The exclusion criteria (cases) were cervical cancer with non-squamous cell histology, cervical cancer patients who were also diagnosed of other malignancies or were receiving treatment for other malignancies, cervical cancer patients that were terminally ill and were receiving palliative radiotherapy treatment, and cervical cancer patients who had benign conditions associated with elevated serum SCC-Ag level. The inclusion criteria (controls) were age ≥ 18 years, females without benign conditions associated with elevated serum SCC-Ag levels, females without current or previous cancer diagnosis of any site, and ECOG performance status 0–3. The exclusion criteria (control) were age < 18 years, females with benign conditions associated with elevated serum SCC-Ag level, females with current or previous cancer diagnosis of any site, and females with poor performance status (ECOG > 3). The benign conditions capable of elevating SCC-Ag levels were excluded by taking a good history from and examining all study participants. The benign conditions excluded were urinary tract disease, such as cystitis and renal failure, lung disease such as tuberculosis, adult pulmonary distress syndrome, and skin disease such as eczema and pemphigus.
Study Measures
The study’s independent variable was serum SCC-Ag level. Participants from both arms of the study were phlebotomized twice, 12 weeks apart. Those with cervical cancer were phlebotomized once before commencement of chemoradiation (which usually lasts 6 weeks) and the second time at 6 weeks after completing chemoradiation. The patients in the control group had two serum SCC-Ag levels drawn; one at baseline and a subsequent test after 12 weeks. Each collected venous blood sample was processed and analyzed for serum SCC-Ag levels immediately upon collection by an ISO (international standards organization)-certified laboratory using Alinity i SCC reagent and Alinity i analyzer from Abbott Laboratory Chicago, IL, USA.
The pre-treatment serum SCC-Ag levels were correlated to the disease stage and grade. Clinical response was divided into four groups using RECIST (Response Evaluation Criteria in Solid Tumors) criteria: complete response (CR), partial response (PR), progressive disease (PD), and stable disease (SD). CR is defined as disappearance of all target lesions. PR is defined as ≥ 30% decrease in the sum of the longest diameters of target lesions compared with baseline. PD is defined as ≥ 20% increase in the sum of the longest diameter of target lesions compared with the smallest-sum longest diameter recorded or the appearance of one or more new lesions. SD is defined as neither partial response nor progressive disease.11
Statistical Analysis
All data from this study, including results of the serum SCC-Ag levels, were analyzed using Statistical Package for Social Sciences (SPSS) version 22. Quantitative variables were tested for normality using Kolmogorov–Smirnov test. The association between pre-treatment SCC-Ag level and disease stage in cervical cancer patients on chemoradiation therapy was determined using Kruskal Wallis. The effect of intervention on SCC-Ag levels was determined using Wilcoxon Signed Rank Test. A logistic regression analysis was done to determine if pre-treatment SCC-Ag levels and SCC-Ag reduction rate were predictive of treatment response in cervical cancer patients on chemoradiation therapy. Alpha (α) was set at 0.05, such that P value < 0.05 was considered statistically significant.
Results
As shown in Table 1, the ages of the cases matched those of the controls, with about 70% of both arms of the study being aged 50 years and above. There was a statistically significant difference between the educational level, occupation, marital status, and type of marriage between the cases and the controls (P = 0.002. 0.005, 0.007 and 0.008 respectively).
Socio-demographic characteristics of study participants
As shown in Table 2, most of the cases (94.7%), presented with vaginal bleeding, whereas 70.7% of cases presented with vaginal discharge. Of the cases, two-thirds (66.6%) were diagnosed at age 50 years and above. About 90% of cases presented with locally advanced disease (Stages 2, 3, and 4). More cases had pelvic than para-aortic node involvement (44% vs. 9.3%). About two-thirds of cases (65.3%) had parametrial involvement, while in 81.3% of the cases, the status of the lymphovascular space was not stated on the histology reports. Most of the cases (94.7%) had no evidence of distant metastasis.
Clinical and tumor characteristics of study participants (cases only)
There were two-thirds of the cases who had tumor size ≥ 4cm. Median post-treatment tumor volume was zero cubic centimeters. More than 90% had SCC of the cervix. About two-thirds of the cases (65.3%) had non-keratinizing cervical carcinoma, and four-fifths (80%) of the cases were not well differentiated.
As shown in Table 3, the serum SCC-Ag level in all study participants in the control group from both the first (baseline) and second (repeat) assays were all within the normal reference range of ≤ 1.5 ng/mL The baseline median SCC-Ag level in the control group was 0.4 ng/ml (IQR of 0.3 – 0.5) and it was comparable to the second (repeat) sample median SCC-Ag level of 0.5 ng/mL (IQR of 0.2 – 0.6). There was a statistically significant difference between the pre-treatment and post treatment median SCC-Ag levels in the cases (P < 0.001), but not in the controls (P = 0.130).
SCC-Ag Levels in study participants
As shown in Figure 1, exactly 74.5% of the cases with normal post treatment SCC-Ag levels had complete response to treatment, while 18.2%, 5.5%, and 1.8% of them had stable disease, partial response, and progressive disease, respectively. Of cases, 65% with elevated post treatment SCC-Ag levels had partial response to treatment; whereas, 20%, 10%, and 5% of them had complete response, progressive disease, and stable disease, respectively.
Treatment Response and Post Treatment SCC-Ag levels.
As shown in Table 4, median SCC-Ag level increased significantly with increasing disease stage (P < 0.001). Though, median SCC-Ag level was decreasing with increasing tumor grade, there was no statistically significant correlation between them (P = 0.159).
Association between pre-treatment SCC-Ag levels and the disease stage and histological grade
Table 5 shows a multivariate analysis (logistic regression model) of three numerical independent variables and four categorical independent variables. The only predictor of treatment response from the regression analysis is the tumor size (P = 0.033). The analysis in this cohort showed cases with tumor sizes < 4 cm, were 87.5% less likely to respond well to treatment compared to cases with tumor sizes > 4 cm (AOR = 0.125). The influence of the other variables tested on the treatment response was not statistically significant.
Predictors of treatment response in participants that underwent treatment
For pre-treatment SCC-Ag, with B = 0.035, AOR = 1.036, and P = 0.451; for every unit rise in pre-treatment SCC-Ag level, there was a 3.6% likelihood of having a positive treatment response, even though it was not statistically significant. For SCC-Ag Decline Rate, with B = 0.699, AOR = 2.012, and P = 0.625; for every unit rise in SCC-Ag decline rate, there was > 100% likelihood of positive treatment response, even though it was not statistically significant. For age at diagnosis, with B = −0.013, AOR = 0.987, and P = 0.753; for every unit rise in age at diagnosis, the likelihood of treatment response decreased by 11% (an inverse relationship), even though it was not statistically significant. For well differentiated histological grade referenced to poorly differentiated histological grade, with B = 0.842, AOR = 2.322, and P = 0.553; well differentiated tumors were 2.3 times more likely to respond positively to treatment compared to those with poorly differentiated tumors, even though it was not statistically significant. For moderately differentiated histological grade, also referenced to poorly differentiated histological grade, with B = 0.393, AOR = 1.481, and P = 0.688; moderately differentiated tumors were 1.5 times more likely to respond positively to treatment compared to those with poorly differentiated tumors, even though it was not statistically significant.
Discussion
This case–control study examined the socio-demographic characteristics in cervical cancer patients and apparently healthy age-matched controls. It assessed the median normal SCC-Ag level in apparently healthy age-matched controls, examined the association between SCC-Ag and the disease stage and grade of cervical cancer, and analyzed the usefulness of SCC-Ag levels in predicting treatment response in cervical cancer cases who received chemoradiation therapy in NLCC and NHA.
The mean age in the cases, 55.9 ± 11.5 years, matched that in the controls, 55.5 ± 11.4 years, which was minimally higher than that from a case-control study by Ketiku et al.12 who found 53.2 years and 51.6 years as the mean ages for the cervical cancer cases and controls respectively. Of the cases, 12% received no formal education, compared with 5.3% of the controls (P = 0.002). The number of professionals in the cervical cancer cases were significantly lower than in the controls (P = 0.005). Also, there were more widows among the cervical cancer cases arm than in the controls (P = 0.007). Significantly, more women were in polygamous relationships among the cervical cancer cases studied compared to the controls. These findings are consistent with those by Ketiku et al.,12 who found low socioeconomic status, low educational level, and polygamy significant risk factors for cervical cancer.
Vaginal bleeding was the most common presenting symptom, present in 94.7% of cases. It was followed by vaginal discharge, present in 70.7% of cases, and 89.3% presented late with locally advanced disease. About half of the cases (44%) had pelvic node involvement, compared to only 9.3% with para-aortic node involvement. These findings were corroborated by Ketiku et al.12 and Silas et al.13
More than 90% of the cases had SCC of the cervix, most of which were non-keratinizing and not well differentiated, with more than two-thirds having tumor size ≥ 4cm. Similarly, Osinachi et al.14 reported 93.2% SCC of the cervix, while Azeez et al.15 reported about 20% well differentiated cervical cancer cases, leaving most of the cases in either moderately well or poorly differentiated grades. Less than one-quarter of the cases (14.7%) were HIV positive, significantly higher than the controls, in whom only 1.3% were positive. Also, 6.7% of the cases did not know their HIV status, a much lower figure than 99.35% of cervical cancer cases who did not know their HIV status as reported by Silas et al.13
With normal serum SCC-Ag set at ≤ 1.5ng/ml, 70.7% of the cases in our study had elevated pre-treatment serum SCC-Ag, of which 66% normalized post-treatment. This is similar to reports from Lee et al.,16 where of 83.5% of patients with elevated pre-treatment SCC-Ag, 60.6% of cases achieved normal post-treatment SCC-Ag levels. There was a statistically significant increase in median SCC-Ag levels with increasing disease stage (P < 0.001). This is similar to the study by Fu et al.,17 where elevated pre-treatment SCC-Ag level was associated with extensive tumors.
Though median SCC-Ag level decreased with increasing tumor grade, the correlation was not statistically significant (P = 0.159). This is similar to the finding by Hong et al.18 (P = 0.53). All members of the control group had normal serum pre- and post-treatment SCC-Ag levels, with mean values 0.4 ng/ml and 0.5 ng/ml, respectively. This is similar to reports by Senekjian et al.19 who found 96% of 99 healthy participants had serum SCC-Ag levels < 2 ng/mL.
A multivariate analysis did not find SCC-Ag reduction rate a predictor of treatment response. Only tumor size (AOR, 0.125 and 95% CI, 0.019 – 0.847; P = 0.033) was found a significant predictor of treatment response in the study participants, in whom pre-treatment SCC-Ag (AOR, 1.036 and 95% CI, 0.946 – 1.134; P = 0.451), pre-treatment SCC-Ag decline rate (AOR, 2.012 and 95% CI, 0.122 – 33.22; P = 0.625), age at diagnosis (AOR, 0.987 and 95% CI, 0.912 – 1.069, P = 0.753), histological grade, pelvic node involvement (AOR, 1.590 and 95% CI, 0.216 – 11.689; P = 0.649), and parametrial node involvement (AOR, 1.490 and 95% CI, 0.235 – 9.439; P = 0.672), were all found non-predictors of treatment response. This is contrary to Fu et al.’s17 finding of SCC-Ag reduction rate as a predictor of treatment response. The analysis also did not find pre-treatment SCC-Ag level a predictor of treatment response. This was similar to the finding by Ngan et al.,20 where SCC-Ag level was found not predictive of treatment response, but persistently elevated SCC-Ag level was however found useful in predicting residual tumor presence.
Our study addresses an important gap by exploring the role of SCC-Ag as a potential marker for assessing treatment response in cervical cancer patients, especially in a Nigerian population, where such studies are limited. The use of a case-control design enhances the validity of the comparisons between cancer patients and healthy controls. Applying RECIST criteria for tumor response ensures standardized evaluation, and the use of age-matched healthy controls helps reduce bias. Furthermore, the study’s collection of both pre- and post-treatment SCC-Ag levels offers valuable insights into the dynamics of this marker throughout treatment. However, a key limitation is that treatment response was assessed primarily through imaging, which may miss microscopic disease and lead to classification bias. Additionally, the use of consecutive sampling might introduce selection bias, as it is not fully randomized. There were baseline differences between cases and controls in variables such as education level and marital status, which may act as confounders. The logistic regression model did not adjust for potential influences like HIV or HPV status, which could have affected the findings. Finally, variability in the timing of SCC-Ag sampling may have impacted the interpretation of SCC-Ag reduction rates, which should be addressed in future studies.
Conclusion
This case-control study demonstrated serum SCC-Ag levels were consistently normal among healthy controls and some post-treatment cervical cancer patients. Elevated pre-treatment SCC-Ag levels correlated significantly with disease stage but not with tumor grade. Importantly, neither pre-treatment SCC-Ag levels nor the rate of SCC-Ag reduction predicted treatment response following chemoradiation, with tumor size emerging as the sole independent predictor. These findings highlight the limited utility of serum SCC-Ag as a predictive biomarker for treatment response in cervical SCC within the Nigerian context, underscoring the need for continued reliance on imaging modalities for response assessment and advocating for further research into accessible and reliable biomarkers for therapeutic monitoring.
Acknowledgements
The authors would like to acknowledge David Puthoff, Ph.D., Scientific Research Writer at the Marshfield Clinic Research Institute – Research Support Services, for his editorial assistance and support in the preparation of this manuscript. His contributions, while invaluable, do not meet the criteria for authorship according to the ICMJE Recommendations.
Footnotes
Disclosures: The authors have declared no conflicts of interest related to this work. This study received no funding.
- Received May 7, 2025.
- Revision received September 8, 2025.
- Accepted September 24, 2025.
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