Levels of circulating tumor cells (CTCs), measured by liquid biopsy, were independently associated with relapse in patients with stage III melanoma, according to a recent study from researchers at the University of Texas MD Anderson Cancer Center. The study was published in Clinical Cancer Research.
“Our findings are significant, given that there is a need for blood-based biomarkers to guide clinical decision making for stage III melanoma patients,” said Anthony Lucci, M.D., professor of Breast Surgical Oncology and Surgical Oncology, and study lead. “There currently are no blood tests available to help doctors accurately tell which patients are likely to relapse, and should be given therapy, and which are low risk, and could be observed.”
More than 100,000 new melanomas are expected to be diagnosed in 2020 in the US alone, and almost 7,000 people there are expected to die from the disease. The rates of melanoma have been rising rapidly over the past few decades.
Although CTCs can be detected in melanoma patients, there is limited data regarding their significance in stage III (node-positive) disease. This prospective study was based on earlier studies that found CTCs in a significant number of breast cancer patients was associated with relapse, independent of other existing methods for determining prognosis. This study adds more evidence to support the theory that CTC assessment may be useful in identifying patients at risk for relapse who could benefit from more aggressive therapy following primary treatment
The researchers assessed CTCs during the patient’s first clinic visit, and relapse-free survival was compared between patients with one or more CTCs, versus those with no CTCs. CTCs were observed in 90 out of 243 patients enrolled in the study. The team prospectively assessed CTCs at first presentation in clinic (baseline) for 243 stage III melanoma patients. CTCs were measured using the CellSearch System. Relapse-free survival (RFS) was compared between patients with one or more baseline CTC results versus those with no CTCs. Log-rank test and Cox regression analysis were applied to establish associations of CTCs with RFS. Results: At least one baseline CTC was identified in 90/243 (37%) patients. Forty-five (19%), 67 (28%), 118 (49%), and 13 (5%) patients were stage IIIA, IIIB, IIIC, or IIID, respectively. CTC detection was not associated with sub stage, or primary tumor characteristics.
“Our analysis demonstrated that CTC detection was significantly associated with a decrease in relapse-free survival at six months, and persisted at a 54-month longer-term follow-up,” said Lucci. “The data from this study provides support for the future pursuit of liquid biopsy techniques to help identify patients most likely to benefit from adjuvant systemic therapy.”
Lucci added that this is vital given that there currently is no clear consensus on when to recommend immunotherapy for node-positive melanoma patients. Despite the development of new targeted and immune therapies to treat melanoma, many patients either do not respond to these therapies or develop resistance to therapy within six to eight months. Because such therapies also can have side effects, avoiding treatment in patients at low risk for relapse may prevent overtreatment.