No abstract

No abstract

BACKGROUND: Actinic keratoses (AKs) are established as direct precursors of squamous cell carcinoma (SCC), but there is significant controversy regarding the rate at which AKs progress to SCC. The authors of this report studied a high‐risk population to estimate the risk of progression of AK to SCC and to basal cell carcinoma (BCC) and the risk of spontaneous regression of untreated AKs. METHODS: Data were obtained from participants in the Department of Veterans Affairs Topical Tretinoin Chemoprevention Trial. Participants were examined every 6 months for up to 6 years. At each examination, the locations on the face and ears of clinically diagnosed AKs and lesions scheduled for biopsy were marked, and high‐resolution digital photographs were taken. These photographs were used later to map and track the presence, absence, or biopsy of each AK across visits. RESULTS: In total, 7784 AKs were identified on the face and ears of 169 participants. The risk of progression of AK to primary SCC (invasive or in situ) was 0.60% at 1 year and 2.57% at 4 years. Approximately 65% of all primary SCCs and 36% of all primary BCCs diagnosed in the study cohort arose in lesions that previously were diagnosed clinically as AKs. The majority of AKs (55%) that were followed clinically were not present at the 1‐year follow‐up, and the majority (70%) were not present at the 5‐year follow‐up. CONCLUSIONS: In the current study, the authors quantified the malignant potential of clinically diagnosed AKs for both SCC and BCC, although many did not persist, and the results suggested that AKs may play a greater role in the overall burden of keratinocyte carcinomas than previously documented. Cancer 2009. Published 2009 by the American Cancer Society.

Over the past two decades, numerous efforts have been initiated to improve screening and early detection of melanoma both in the United States and worldwide. It is commonly believed that these efforts have contributed to the stabilization of melanoma mortality, and that the proportion of thick melanoma with unfavorable prognosis is on the decline. Data obtained from 17 population-based cancer registries of the Surveillance Epidemiology and End Result (SEER) program of the National Cancer Institute for 1988-2006 were used to examine trends in melanoma tumor thickness. For malignant melanoma cases with recorded thickness, the proportionate distribution among four thickness categories (4 mm) remained relatively stable over the 19-year study period, however, for melanomas resulting in death, the proportion of thick tumors increased. The most substantial change occurred in the proportion of melanoma in situ, which nearly doubled from 1988 to 2006. Surveillance and early detection efforts in the United States have not resulted in a substantial reduction in the proportion of tumors with prognostically unfavorable thickness. Continued improvement and new methods of screening, especially among demographics with higher incidence of thick tumors, is necessary.