A team of researchers from the Geisel School of Medicine at Dartmouth, have examined the individual risk factors correlated with the development of subsequent cancers after non-melanoma skin cancer. The study, titled “Non Melanoma Skin Cancer and Subsequent Cancer Risk” was published in the PlosOne journal.
Non-melanoma skin cancers (NMSC) are the most frequently diagnosed malignancies in the United States, and can be divided into two major types: basal cell (BCC) and squamous cell carcinoma (SCC). Even though these types of cancer do not hold a major impact on mortality, their public health impact is considered significant.
There have been several studies showing that patients who are diagnosed with non-melanoma skin cancers have an increased chance (20–60%) of suffering from second primary malignancies. Even though these reports included large, well-defined populations, they lacked detailed individual cancer risk factor data, like family history of cancer and dietary information.
In this study, the team analyzed data from the population-based New Hampshire Skin Cancer Study, identifying subsequent cancers through linkage with the state cancer registry. Moreover, mortality rates were assessed through state and national death records. The authors used defined statistical analysis to estimate risk of subsequent malignancies in NMSC patients and to evaluate the potential confusing effects of multiple risk factors on this risk.
The results demonstrated that among the 3,584 subjects who participated in the study, the risk of developing a successive cancer was increased after basal cell carcinoma (BCC) than squamous cell carcinoma (SCC), when compared to controls. These results had in consideration and were adjusted for age, sex and cigarette smoking habits.
The authors also found that the risk of developing a subsequent cancer was higher among patients who were diagnosed before the age of 60 years, and that patients who suffered from SCC had a three-fold risk of developing melanoma later on in life, even after adjustments for sun exposure-related factors and family history of skin cancer. Also, in male patients, prostate cancer incidence was higher after BCC, when compared to controls.
Even though this study did not conclude that sun exposure affected non-skin cancer risk, it could be that the population sample size was not big enough to detect this link. However, the authors write that they identified “an excess risk of melanoma following both BCC and SCC with significantly increased melanoma risk in participants reporting a family history of NMSC, but not a family history of melanoma which is a known risk factor for melanoma”. They further concluded that, “melanoma risk was also increased among individuals who peel or develop moderate tans upon chronic sun exposure (compared to those who develop a deep tan). Former smokers had a significantly lower risk of melanoma after NMSC and a risk reduction was seen in current smokers but this could have been due to chance”.