The annual meeting of The American Society of Clinical Oncology (ASCO) always produces headlines about advances made in detection, treatment and prevention of cancer, and this year those headlines include news for the anal cancer community.
Dr Van Morris and his team at MD Anderson announced results from their study of circulating tumor DNA (ctDNA). They assessed ctDNA as a potential biomarker to predict outcomes for patients undergoing standard chemoradiation treatment for localized anal cancer. The study measured HPV ctDNA before, during, and after treatment in patients with anal cancer. HPV ctDNA presence three months after chemoradiation was associated with an increased risk of cancer recurrence.
Background
Anal cancer, often caused by HPV infection, is becoming more common in the United States. The standard treatment is a combination of chemotherapy and radiation (cRT). Finding detectable levels of circulating tumor DNA (ctDNA) in the blood after treatment can predict if the cancer will come back, but the best time to test for this in anal cancer patients hasn't been clear. This study looks at whether testing for HPV ctDNA in the blood can help predict outcomes for patients treated with cRT.
Methods
Patients with early to moderately advanced anal cancer were tested for HPV ctDNA before treatment, at the end of treatment (after 5 weeks) and then 3, 6, 9, and 12 months after finishing treatment. A test was used to detect HPV ctDNA in the blood.
Results
- Detection Rates: HPV ctDNA was found in 22% of patients at the end of treatment, 13% at 3 months, 10% at 6 months, and none at 12 months.
- Recurrence Prediction: If HPV ctDNA was detected 3 months after treatment, the cancer almost recurred (100% of the time), compared to just 8% when ctDNA was not detected. Patients with detectable ctDNA at 3 had return more quickly (at about 6 months) compared to those without ctDNA
- Early Detection: When testing immediately after treatment at 5 weeks, there was not an association between ctDNA detection and recurrence.
- Accuracy: The 3-month test was very reliable, with a perfect score in predicting cancer return when ctDNA was found, and nearly 90% accuracy when ctDNA was not found.
Conclusions
Testing for HPV ctDNA in the blood 3 months after treatment is a strong indicator of whether anal cancer will come back. Future studies should use this 3-month marker to identify patients at high risk.
Study abstract
https://meetings.asco.org/abstracts-presentations/234204
More information
webinar: The role of circulating tumor DNA in management of anal cancer with Dr Van Morris.
