What this Trial Is About

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.

Dynamic ctDNA Assessment in Cervical and Anal Canal Tumors: Optimizing Follow-up and Clinical Outcomes