Abstract 5015: Tumor infiltrating lymphocytes and regression in cutaneous melanoma in the elderly: A link with clinical behavior

Abstract

Abstract Background: The incidence of melanoma in patients ≥65 years has increased threefold over the past 25 years. Differences in melanoma biology and host factors such as immunosenescence may contribute to the adverse prognostic effect of age and sex on outcome. Tumor-infiltrating lymphocytes (TILs) and regression are considered a manifestation of the host immune response to tumor, but the influence of TILs and regression on outcome remains controversial. We undertook the present study to evaluate the association of these factors with other prognostic markers and outcome among elderly melanoma patients in our community surgical oncology practice. Methods: From our Melanoma Registry we identified 250 consecutive cutaneous melanoma patients aged ≥65 years (median 75, range 65-97 years) at the time of diagnosis of their index primary melanoma. Patient and tumor data were verified by individual record and report review. Mean (median) follow up for surviving patients was 72±3.8 (65) months. An SAS software package was used for statistical analysis. Results: 134 patients (54%) were male and 98% were Caucasian. Melanoma site was extremity in 42%, trunk in 32% and head/neck in 23%. The most common histologic type was superficial spreading (43%), mean tumor thickness was 1.4±0.1 mm, 16% were ulcerated, the mean mitotic index was 2.88±0.47, a brisk TIL infiltrate was seen in 24%, non-brisk TIL in 15% and regression in 13%. T stage distribution included 36% T1, 14% T2, 14% T3 and 9% T4 tumors. 6% of patients had lymph node (LN) metastases. LN metastases were more prevalent in male (11%) than female (3%) patients, p=0.007 and more prevalent in patients with melanomas with brisk TILs (16%) than absent/non-brisk TILs (4%), p=0.02. There were no significant sex differences in TILs or regression. During follow up, 22% of patients recurred, 21% died of unrelated causes and 12% died of melanoma. The mean (median) time to recurrence was 33.8 ± 5.3 (16) months. Recurrence was 4-fold greater in patients with absent/non-brisk TILs (22%) than with brisk TILs (5%), p=0.02, and two-fold greater in male (27%) than female (14%) patients, p=0.01. Regression was not predictive of recurrence. Disease-free survival (DFS) was worse for male than female patients: 5 y (10 y) DFS 68% (64%) vs 84% (72%), p=0.005, and worse for patients with absent/non-brisk TILs than brisk TILs: 5 y (10y) DFS 76% (71%) vs 91% (90%), p=0.06. Conclusions: A brisk TIL infiltrate, together with female sex, was associated with a diminished risk of recurrence after treatment of cutaneous melanoma in our elderly patient population, despite the finding that brisk TILs conferred a 4-fold greater risk for LN involvement. Further investigation of the clinical significance and applicability of these apparently paradoxical findings is warranted. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5015. doi:10.1158/1538-7445.AM2011-5015