Will the melanoma metastasize?
Scientists have developed a new method for predicting the spread of melanoma
Scientists have found that patients with a low proportion of T-lymphocytes are 2.5 times more likely to metastasize skin cancer than patients with higher levels of T-cells. The results of the study are published in the journal Nature Cancer (Pruessmann et al., Molecular analysis of primary melanoma T cells identifies patients at risk for metastatic recurrence).
In most patients, skin cancer begins with a small pigmented spot on the skin, which begins to change over time. Sometimes it is enough to remove the primary melanoma to stop the disease, but often this does not help, and the tumor can recur and spread as metastases.
Scientists have found that the analysis of a remote lesion can provide information about the likelihood of cancer returning. Researchers from Boston Brigham Women's Hospital (USA) in collaboration with foreign colleagues have developed a new quantitative technique that uses DNA sequencing for more complex and accurate predictions of which primary melanomas may recur and spread after surgery to remove them.
"Even 10 years ago, the prospects for patients with metastatic melanoma were very gloomy," Thomas Kupper, one of the authors of the study, MD, head of the Department of Dermatology, is quoted in the hospital's press release. "But now we have immunotherapeutic methods of treatment that can be used even before metastasis begins, but for this it is important to have a clear idea of which patients the disease can progress and which do not, in order to choose the right treatment."
A feature of melanoma is a weak response of the body or its absence to cancer cells, which is why the tumor often progresses rapidly. The situation has changed radically with the advent of so-called immune checkpoint inhibitors, which can awaken T cells to form an immune response. In some patients, the use of such inhibitors forms a long–term remission - in fact, the patient is cured, and in some the disease continues to progress.
The researchers compared samples of the removed material of patients whose primary melanoma had progressed to metastasis with those whose primary melanoma had not progressed. Using the methods of adaptive biotechnologies, the authors conducted DNA sequencing and analyzed the composition of tumor T cells.
It turned out that the main indicator of the probability of tumor progression is the number of T cells in the lesion (TCFr indicator). Patients with TCFr less than 20 percent were more at risk of disease progression than patients with TCFr more than 20 percent. For example, in patients with stage T3 melanoma (2-4 mm thick), five years after the initial operation, the disease returned in 51 and 24 percent of cases, respectively.
"This is a very simple, elegant test. It is quantitative, not subjective, and can increase the value of predictions about the progression of the disease," says Kupper. "In the future, such a test will help to adapt treatment: patients with high TCFr will undergo therapy with checkpoint inhibitors, and those with low TCFr may need additional surgery."
The authors note that the current study is retrospective, since it examined samples of patients whose treatment results are already known. Further testing of the test will require clinical trials.
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