What factors are associated with the poor prognosis of anal adenocarcinoma compared with low-lying rectal adenocarcinoma based on a population analysis: A propensity score matching study

Survival outcomes of anal adenocarcinoma versus rectal adenocarcinoma: A retrospective cohort study

BACKGROUND

Anal adenocarcinoma (AA) is a rare malignancy with decreased survival compared to rectal adenocarcinoma (RA). However, AA continues to be treated with similar algorithms compared to rectal cancer with minimal data regarding the efficacy of these treatment algorithms.

METHODS

A retrospective chart review of patients with non-metastatic AA at a single tertiary-care institution from 1995 to 2020. This cohort was matched 2:1 to a group of RA patients for comparison. The primary outcome of interest was overall survival rates.

RESULTS

Sixteen patients with stages I-III AA were matched to a cohort of RA. There were no significant differences between the cohorts with regard to patient demographics, comorbidities, disease stage or histologic features. There were also no significant differences in treatment modalities between the two cohorts with a majority undergoing multimodal therapy with chemoradiation and surgery. All patients with AA demonstrated significantly worse survival than all patients with rectal adenocarcinoma (five-year survival 47.7% vs. 82.3%, respectively. p < 0.05). When looking at a sub-group of patients who underwent combination chemoradiation and surgery from each cohort, anal adenocarcinoma continued to exhibit lower overall survival (five-year survival 41.6% and 86.4%, respectively. p < 0.05). In a multi-variable model that adjusted for location, American Joint Committee on Cancer (AJCC) stage and treatment pathway, tumor location in the anal canal was an independent predictor of overall survival (Hazard ratio [HR] 2.7, p < 0.05).

CONCLUSION

AA has worse survival as compared to RA despite similar treatment. This study highlights the need to evaluate the current classification and treatment pathways to improve outcomes.

Clinical characteristics and prognostic factors of anal adenocarcinoma: a nomogram development based on SEER database and validation in the WCH database

PURPOSE

The purpose of this study was to comprehensively understand anal canal adenocarcinomas (AA) and develop a nomogram for prognostic prediction of AA.

METHODS

Data were extracted from the Surveillance, Epidemiology, and End Results (SEER) database (the year 2004-2015). An external validation set was collected from West China Hospital (WCH) databases. Propensity-score matching (PSM) was performed to balance the demographic characteristic. A novel nomogram was developed to estimate individual survival probability and its performance was validated using the concordance index (C-index), calibration curves, and decision curve analyses (DCA).

RESULTS

A total of 7901 patients were enrolled including 749 AA patients and 7152 squamous cell carcinomas of the anal canal (ASCC) patients. Before PSM, patients with AA had shorter cancer-specific survival (CSS) and OS than those with ASCC. However, after PSM, patients with AA were related to a favorable OS (p < 0.001), but a comparable CSS (p = 0.140) to those with ASCC. Age, sex, grade, surgery, and M stage were the independent prognostic factors of CSS for AA and were included in the establishment of a novel nomogram. Patients from the WCH database (n = 112) were used as an external validation cohort. The C-index of the nomogram was 0.78 and 0.735 in internal and external validation, respectively, which suggested the good discrimination power of the model. Furthermore, calibration curves and DCA suggested good agreement between the predicted and actual survival. Lastly, a risk classification system based on a nomogram revealed the reliability of the novel model.

CONCLUSION

AA and ASCC had distinct clinical features. AA was associated with a better prognosis than ASCC after PSM. The model of nomogram showed an accurate predictive ability for prognostic factors of AA patients.

Management and Outcomes in Anal Canal Adenocarcinomas—A Systematic Review

Simple Summary

Anal canal adenocarcinomas are a rare type of bowel cancer. For this reason, it is challenging to perform large studies in order to determine the optimal treatment strategy to achieve the best outcomes. Options for treatment include radiotherapy, chemotherapy and surgery. These treatments may be combined or used alone. Outcomes are regarded as survival after diagnosis and treatment, or the recurrence of the disease. There is no universal gold standard that exists, with wide variability in practice and therefore also in outcomes between institutions. Thus, by reviewing the body of literature on the subject matter, the hope is to establish a management algorithm that may be tested and refined going forward. This is the intention of this systematic review.

Abstract

(1) Background: Anal canal adenocarcinomas constitute 1% of all gastrointestinal tract cancers. There is a current lack of consensus and NICE guidelines in the United Kingdom regarding the management of this disease. The overall objective was to perform a systematic review on the multitude of practice and subsequent outcomes in this group. (2) Methods: The MEDLINE, EMBASE, EMCARE and CINAHL databases were interrogated between 2011 to 2021. PRISMA guidelines were used to select relevant studies. The primary outcome measure was 5-year overall survival (OS). Secondary outcome measures included both local recurrences (LR) and distant metastases (DM). The Newcastle–Ottawa Scale (NOS) was used to assess the quality of studies retrieved. The study was registered on PROSPERO (338286). (3) Results: Fifteen studies were included. Overall, there were 11,967 participants who were demographically matched. There were 2090 subjects in the largest study and five subjects in the smallest study. Treatment modalities varied from neoadjuvant chemoradiotherapy (CRT), CRT and surgery (CRT + S), surgery then CRT (S + CRT) and surgery only (S). Five-year OS ranged from 30.2% to 91% across the literature. LR rates ranged from 22% to 29%; DM ranged from 6% to 60%. Study heterogeneity precluded meta-analysis. (4) Conclusions: Trimodality treatment with neoadjuvant chemoradiotherapy (CRT) followed by radical surgery of abdominoperineal excision of rectum (APER) appeared to be the most effective approach, giving the best survival outcomes according to the current data.

Prognosis of anal canal adenocarcinoma versus lower rectal adenocarcinoma in Japan: a propensity score matching study

PURPOSE

Anal canal adenocarcinoma (AC) is rare and its surgical outcomes and prognostic factors (PFs) are not well understood. The aim of this retrospective study was to identify the characteristics and PFs of AC, using population-based data in Japan.

METHODS

Patients with AC (n = 390) or lower rectal adenocarcinoma (LR) (n = 12,477) diagnosed between1991 and 2006 were enrolled in this study. We compared the clinical- and patient-related factors of the two diseases and then examined propensity score matching, overall survival (OS), and PFs.

RESULTS

AC tended to develop more often in women and in patients of advanced age. Macroscopically, AC was of an unclassified type and microscopically, it was of high-grade histological types such as mucinous adenocarcinoma, poorly differentiated adenocarcinoma (por), or signet-ring cell carcinoma (sig), with a high frequency of inguinal node metastasis (P < 0.05). The 5 year OS rates were 56.9% for AC and 67.9% for LR (P = 0.002). The PFs of AC were a high-grade histological type (por/sig), T, N, and M.

CONCLUSIONS

AC has a significantly worse prognosis than LR. Moreover, the AC lymph node metastatic sites for AC, especially the inguinal nodes, are different from those for LR.