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According to a recent study published in the Journal of the American Academy of Dermatology, tumor-infiltrating lymphocytes (TILs) predict prognosis for primary melanoma in men, but not women.
TILs are lymphocytes present within tumors, and in the case of primary melanoma, they are found alongside melanoma cells. They elicit immunity locally and may decrease the likelihood of sentinel lymph node (SLN) metastases. Men and women differ in immunity, forming the basis of this study.
The clinical sample comprised 1367 patients, 794 of whom were men. Inclusion in the study required clinically localized primary melanoma that was ≥0.76 mm in Breslow thickness in patients undergoing SLN biopsy.
TILs were classified as “absent” (none present), “brisk” (found throughout the entire tumor or across the entire base), or “nonbrisk” (all other patterns). Logistic regression was used to calculate the association between TIL classification and SLN positivity. Overall survival was also calculated in association with TIL classification and sex.
TIL status (brisk, n=143 lesions; nonbrisk, n=903; absent, n=321) evidenced no association with sex (P =.71). However, SLN positivity was associated with TIL classification in men (brisk, 3.8%; nonbrisk, 16.9%; absent, 26.6%; P <.001), but not women (P =.49). Furthermore, significant interaction was evidenced between brisk TILs and sex on SLN positivity (P =.029). Overall survival was associated with the presence of brisk TILs in men (P =.038), but not women, until it was adjusted for SLN status (P =.42).
The study may be limited by misclassification bias resulting from potential variability in TIL classification, as well as selection bias resulting from the inclusion of only patients with TIL data.
“Pending validation by other research groups, this data may help risk stratify male patients for SLN metastases and aid in selection of patients to undergo the SLN [biopsy] procedure,” the authors wrote. “The finding that TILs is not prognostic for survival independent of SLN status suggests that TILs could be used for clinical decision-making for patient selection to undergo SLNB, but likely should not be used for further prognosticating beyond that.”
Reference
Sinnamon AJ, Sharon CE, Song Y, et al. The prognostic significance of tumor-infiltrating lymphocytes for primary melanoma varies by sex [published online March 5, 2018]. J Am Acad Dermatol. doi: 10.1016/j.jaad.2018.02.066
