Anal Canal Cancer

After definitive radiotherapy (RT) treatment (with or without chemotherapy), cervical and anal canal neoplasms frequently exhibit disease persistence or recurrence. Due to the local inflammatory process post-treatment, response assessment by imaging (current gold standard) is limited, often necessitating multiple follow-ups and repeated invasive biopsies. Conventional follow-up is complex and costly, requiring equipment from secondary and tertiary services, trained radiologists, and patient exposure to radiation and contrast. In this context of human papillomavirus(HPV)-related neoplasms, recent studies have demonstrated the role of ctDNA (circulating tumor DNA) in assessing the risk of recurrence or disease progression, providing a rationale for using the tool in two fronts: * Optimizing follow-up based on serial monitoring of ctDNA; * Selecting patients with positive ctDNA after RT, who are at high risk of recurrence, for treatment intensification. Monitoring with ctDNA as a standalone follow-up tool in cases evolving with negative ctDNA after RT has the potential to replace imaging exams, being a minimally invasive test performed on a peripheral blood sample. Currently, ctDNA testing has expensive methodologies not available in the Unified Health System (SUS). This project aims to develop a methodology for ctDNA evaluation focused on HPV ctDNA research that is low-cost and executable in SUS, as well to assess the accuracy of this test in the population with HPV-related tumors. Additionally, we will evaluate whether the early introduction of immunotherapy in patients with positive ctDNA after definitive treatment can increase cure rates. Immunotherapy already has a well-defined role in the treatment of metastatic HPV-related neoplasms. Recently, the use of anti-programmed death-1 (anti-PD1) has also shown benefits in patients with locally advanced cervical cancer with a high risk of recurrence who are candidates for chemoradiotherapy (CRT). Therefore, its use focused on HPV-related tumors, as well as a better understanding of which patients benefit from this strategy, warrants further investigation.

The purpose of this study is to see whether avoiding preventative radiation to the groin in patients with normal sentinel node biopsy and PET-CT, is at least as effective treating cancer as giving preventative radiation to the groin for patients with anal canal cancer. The investigators also want to know if avoiding radiation to the groin will cause fewer side effects and better quality of life

The main aim of the SANCA study is to evaluate the feasibility, cost-effectiveness, and acceptability of implementing international anal cancer screening guidelines for women living with HIV in Sweden, integrating health economic and patient-centered approaches. Secondly the investigators wish to investigate the predictive potential of DNA methylation markers for the clinical progression of precancerous anal lesions in women with HIV, combining prospective molecular biology analysis with clinical data from registries.

This is a Phase II study to determine the efficacy of SBRT to treat liver metastases in patients with Colorectal Adenocarcinoma, Carcinoma of the Anal Canal and Gastrointestinal Neuroendocrine Tumors that are not amenable to surgery. Patients should have no evidence of extra-hepatic disease or have disease that is planned to be treated with curative intent. Therefore, SBRT is being considered as a potentially curative procedure.