The prognostic importance of tumor mitotic rate confirmed in 1317 patients with primary cutaneous melanoma and long follow-up.

BACKGROUND: The late Dr. Vincent McGovern (1915 to 1983) was an international authority on melanoma pathology and one of the first to suggest that assessment of tumor mitotic rate (TMR) might provide useful prognostic information. Data for a large cohort of patients, now with extended follow-up, whose tumors had been assessed by Dr. McGovern were analyzed to reassess the independent prognostic value of TMR in primary localized, cutaneous melanoma. METHODS: Information was extracted from the Sydney Melanoma Unit database for 1317 patients treated between 1957 and 1982 for whom there was complete clinical information and whose primary lesion pathology, which included tumor thickness, ulcerative state, and TMR, had been assessed by Dr. McGovern. All these assessments were made according to the recommendations of the Eighth International Pigment Cell Conference, held in Sydney in 1972 under the auspices of the International Union Against Cancer. Factors predicting melanoma-specific survival were analyzed with the Cox proportional hazards regression model. RESULTS: Stage, according to the recently revised American Joint Committee on Cancer Staging System (which is based on tumor thickness and ulceration) was the most predictive factor for survival (P<.0001). This was followed by primary lesion site (P<.0001), patient age (P=.0005), and TMR (P=.008). CONCLUSIONS: TMR was confirmed to be an important independent predictor of survival of patients with primary cutaneous melanoma. However, its predictive value was less than it was when assessed according to the 1982 revisions of the 1972 TMR recommendations.

Tumor mitotic rate is a more powerful prognostic indicator than ulceration in patients with primary cutaneous melanoma: an analysis of 3661 patients from a single center.

BACKGROUND: The current study was performed to determine whether tumor mitotic rate (TMR) is a useful, independent prognostic factor in patients with localized cutaneous melanoma. METHODS: From the Sydney Melanoma Unit database, 3661 patients with complete clinical information and details of primary tumor thickness, ulcerative state, and TMR were studied. TMR was expressed as mitoses per mm(2) in the dermal part of the tumor in which most mitoses were seen, as recommended in the 1982 revision of the 1972 Sydney classification of malignant melanoma. To determine which was the more prognostically useful method of grouping TMR, two separate methods (A and B) were used. Factors predicting melanoma-specific survival were analyzed using the Cox proportional hazards regression model. RESULTS: Patients with a TMR of 0 mitoses/mm(2) had a significantly better survival than those with 1 mitosis/mm(2) (P < 0.0001) but no significant survival differences were recorded for the stepwise increases from 1-2, 2-3, 3-4, and 4-5/mm(2). Tumor thickness, ulceration, and TMR were closely correlated, whether TMR was grouped using Method A (0, 1-4, 5-10, and >/= 11 mitoses/mm(2)) or Method B (0-1, 2-4, and >/= 5 mitoses/mm(2)). However, Cox regression analysis indicated that the TMR was a highly significant independent prognostic factor, particularly when grouped according to Method A, in which it was second only to tumor thickness as the most powerful predictor of survival (P < 0.0001). CONCLUSIONS: TMR is an important independent predictor of survival for melanoma patients. If confirmed by studies from other centers, it has the potential to further improve the accuracy of melanoma staging, as well as to define more rigidly the risk categories for patients entering clinical trials.