WINNIPEG, MAN. — People who developed their first basal cell carcinoma or squamous cell carcinoma had a higher risk of developing and dying of a second primary cancer, data from a retrospective study of 43,275 patients showed.
A first basal cell carcinoma quadrupled the relative risk for melanoma in men, tripled the risk for melanoma in women, and raised women's risk for lip cancer fivefold. Men with a first primary squamous cell cancer had nine times the risk for salivary gland cancer, compared with men without the first cancer, Dr. Marni C. Wiseman said.
Death from esophageal cancer was seven times more likely in men and five times more likely in women if they'd had a first primary nonmelanoma skin cancer. A first squamous cell cancer increased the risk of death from Hodgkin's lymphoma 14-fold in men. Death from genitourinary cancer was three to four times more common in women after a first primary basal or squamous cell carcinoma, she said at the annual conference of the Canadian Dermatology Association.
The study looked at cancer-free people who developed a first primary nonmelanoma skin cancer between 1956 and 2000. These cancers seldom are treated with systemic therapy or chemotherapy that might alter a patient's chances of getting unrelated second primary cancers, said Dr. Wiseman of the department of dermatology at the University of Manitoba, Winnipeg, and director of cutaneous oncology at CancerCare Manitoba. Patients in the Manitoba Cancer Registry, which recorded other cancers but excluded second nonmelanoma skin cancers, were tracked.
Of the first primary nonmelanoma skin cancers, 21% were squamous cell carcinoma, 74% were basal cell carcinoma, and 5% were other nonmelanoma skin cancers. Of patients in the squamous cell cancer group, 16% developed a second primary nonmelanoma skin cancer, as did 17% of patients in the basal cell carcinoma group.
Compared with people who had no history of nonmelanoma skin cancer, men diagnosed between the ages of 40 and 79 years and women diagnosed between the ages of 40 and 74 years with basal or squamous cell carcinoma had a higher risk for a second primary cancer.
Overall, the risk remained elevated for only 4 years following diagnosis of the primary nonmelanoma skin cancer, except in women originally diagnosed with squamous cell carcinoma, whose risk stayed elevated. For patients diagnosed with a first primary basal or squamous cell carcinoma at a young age (under 60 years), however, the risk of a second primary cancer was permanently elevated, ranging from a relative risk of 1.07 to 1.51 depending on sex and type of first cancer. In general, the lifetime risk of developing a first primary basal cell or squamous cell cancer is common—14% in men and 16% in women.
Dr. Wiseman said it is not known why the risk for a second primary cancer and death is increased, but it is reasonable to think that in some patients, a nonmelanoma skin cancer may be a “first glimpse” of overall cancer-prone status.