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New research suggests people who develop frequent cases of basal cell carcinoma (BCC) have an increased risk of leukemias, lymphomas, and other cancers.

“We discovered that people who develop 6 or more basal cell carcinomas during a 10-year period are about 3 times more likely than the general population to develop other, unrelated cancers,” said Kavita Sarin, MD, PhD, of Stanford University School of Medicine in California.

“We’re hopeful that this finding could be a way to identify people at an increased risk for a life-threatening malignancy before those cancers develop.”

Dr Sarin and her colleagues reported their findings in JCI Insight.

Stanford cohort

The researchers first studied 61 patients treated at Stanford Health Care for unusually frequent BCCs—an average of 11 per patient over a 10-year period. The team investigated whether these patients may have mutations in 29 genes that code for DNA damage repair proteins.

“We found that about 20% of the people with frequent basal cell carcinomas have a mutation in one of the genes responsible for repairing DNA damage, versus about 3% of the general population,” Dr Sarin said. “That’s shockingly high.”

Specifically, there were 12 BCC patients (19.7%) who had 13 pathogenic mutations in 12 genes—APC, BARD1, BRCA1, BRCA2, CDH1, CHEK2, MLH1, MSH2, MSH6, MUTYH, NBN, and PALB2. And 3.0% of non-Finnish European subjects in the Exome Aggregation Consortium had pathogenic mutations in these 12 genes.

Furthermore, 21 of the 61 BCC patients (64.4%) had a history of additional cancers. This included 5 hematologic malignancies (leukemia/lymphoma), 5 invasive melanomas, and 2 breast, 2 colon, and 5 prostate cancers.

When the researchers compared the cancer prevalence in these patients to the Surveillance, Epidemiology, and End Results-estimated prevalence of cancer in the 60- to 69-year-old population of European descent, the BCC cohort had an increased risk of any cancer—a relative risk (RR) of 3.5 (P<0.001).

The RR was 3.5 for leukemia and lymphoma (P=0.004), 11.9 for invasive melanoma (P<0.001), 4.5 for colon cancer (P=0.030), 5.6 for breast cancer (P=0.009), and 4.7 for prostate cancer (P<0.001).

Insurance cohort

To confirm the findings in the Stanford cohort, the researchers applied a similar analysis to a large medical insurance claims database, Truven MarketScan.

The database contained 111,562 patients with 1 case of BCC, 13,264 patients with 6 or more BCCs, and 2920 patients with 12 or more BCCs. Truven patients with no history of BCC served as controls.

The researchers adjusted for age and sex and found that patients with 1 BCC, 6 or more BCCs, and 12 or more BCCs had an increased risk of any cancer compared to controls.

The odds ratio (OR) for any cancer was 1.61 for patients with 1 BCC, 3.12 for those with 6 or more BCCs, and 4.15 for patients with 12 or more BCCs.

The OR for Hodgkin lymphoma was 2.27 for patients with 1 BCC, 8.94 for patients with 6 or more BCCs, and 15.41 for patients with 12 or more BCCs.

The OR for non-Hodgkin lymphoma was 1.40 for patients with 1 BCC, 2.59 for patients with 6 or more BCCs, and 3.10 for patients with 12 or more BCCs.

The OR for leukemia was 1.76 for patients with 1 BCC, 3.23 for patients with 6 or more BCCs, and 5.78 for patients with 12 or more BCCs.

The researchers pointed out that, the more BCCs an individual had, the more likely that person was to have had other cancers as well.

“I was surprised to see such a strong correlation, but it’s also very gratifying,” Dr Sarin said. “Now, we can ask patients with repeated basal cell carcinomas whether they have family members with other types of cancers and perhaps suggest that they consider genetic testing and increased screening.”

The researchers are continuing to enroll Stanford patients in their study to learn whether particular mutations in genes responsible for repairing DNA damage are linked to the development of specific malignancies. The team would also like to conduct a similar study in patients with frequent melanomas.

The current study was supported by the Dermatology Foundation, the Stanford Society of Physician Scholars, the American Skin Association, and Pellepharm Inc.

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