Tumor Histology Is an Independent Prognostic Factor in Locally Advanced Cervical Carcinoma

Background: Even with different histologic origins, squamous cell carcinoma (SCC) and adenocarcinoma (AC) are considered a single entity, and the first-line treatment is the same. Locally advanced disease at the diagnosis of cervical cancer is the most important prognostic factor, and even though treatment is very well standardized, the recurrence rate is still high, making it necessary to evaluate prognostic factors other than clinical or radiological staging; histology could be one of them but continues to be controversial. The aim of this study was to evaluate tumor histology as a prognostic factor in terms of treatment outcomes, disease-free survival (DFS) and overall survival (OS) in a retrospective cohort of patients with locally advanced cervical cancer (LACC) treated with standard chemoradiotherapy in a reference center in Mexico. Methods: The records of patients with LACC were reviewed. A total of 1291 patients were suitable for the analysis, and all of them were treated with 45-50 Gy of external bean radiotherapy (EBRT) with at least three doses of concurrent chemotherapy and brachytherapy. A descriptive and comparative analysis was conducted. Treatment response was analyzed by the chi-square test; DFS and OS were calculated for each histology with the Kaplan-Meier method and compared with the log-rank test; and the Cox model was applied for the multivariate analysis. The results were considered statistically significant if p<0·05. Results: We included 1291 patients with LACC treated from 2005 to 2014, of which 1154 (89·4%) had SCC and 137 (10·6%) had AC. Complete response to treatment was achieved in 933 (80·8%) patients with SCC and 113 (82·5%) patients with AC. Recurrence of the disease was reported in 29·9% of SCC patients and 31·9% of AC patients, with no differences between the groups. The median follow-up was 61·5 months (range 0-181 months). Five-year DFS was 70% for SCC and 62·2% for AC. The five-year OS rates were 74·3% and 60% for SCC and AC, respectively. The mean DFS was 48·8 months for SCC vs 46·10 for AC (p=0·043), and the mean OS was 50·8 for SCC and 47·0 for AC (p=0·002). Conclusion: Our findings support the hypothesis that SCC and AC are different clinical entities. Prospective studies are warranted to include histological types when developing treatments for patients with LACC. Funding Statement: National Cancer Institute, Mexico Declaration of Interests: The author has completed the ICMJE uniform disclosure form. The authors declare that they have no conflicts of interest. Ethics Approval Statement: This study was approved by our IRB, with approval reference Rev/050/18.