Melanoma growth rate objectively measured in sequential biopsies
Source: Healio.com, Dermatology, October 2014
Researchers were able to obtain an objective measure of melanoma growth rate by reviewing sequential biopsy specimens from initial misdiagnoses, as opposed to relying on subjective patient recall. Faster growth rates were associated with increased tumor thickness, high mitotic rate, symptoms, elevation and amelanosis, which coincides with previous research.
In the retrospective review, researchers calculated rate of growth by measuring the rate of increase in melanoma thickness between two sequential partial biopsy specimens over time in 51 melanoma cases.
The cohort was divided into two groups (1) melanomas in which the first biopsy was obtained while in its in situ phase and (2) melanomas in which the first biopsy was obtained while the melanoma was considered an invasive tumor, according to the study.
The median delay between the two biopsy specimens was 27 months.
In melanomas where the first biopsy was taken in situ, the median growth rate was 0.02 mm/month for thin tumors, and 0.06 mm/month for intermediate thickness tumors and 0.15 mm/month for thick tumors.
In melanomas that were considered invasive at initial biopsy, the median growth rate was 0.01 mm/month for thin tumors, 0.09 mm/month for intermediate thickness tumors and 0.35 mm/month for thick tumors.
In the invasive tumor group, a median ROG of 0.05 mm/month was found in superficial spreading melanomas, 0.06 mm/month for lentigo maligna melanomas, 0.21 mm/month for acral lentiginous melanomas, and 0.51 mm/month for desmoplastic melanomas.
Amelanotic tumors grew six times faster than pigmented tumors in the invasive tumor group.
Researchers found a faster growth rate coincided with a higher mitotic rate. Also, symptomatic tumors were also more likely to have faster growth.
The researchers preferred rate of growth from tumors that were invasive at initial biopsy as a more reliable measure of growth compared to rate of growth in tumors that were in situ, as the duration of the in situ phase is uncertain, according to the study.