New research from Mayo Clinic finds that patients with lymphedema—swelling of the limbs caused by the accumulation of protein-rich fluids of the immune system—had twice the risk of developing skin cancer than patients without lymphedema.

Patients with lymphedema had a significantly higher frequency of developing basal cell carcinomas and squamous cell carcinomas on the lower extremities, according to the retrospective study published in Mayo Clinic Proceedings. The study contributes to growing information linking lymphedema to localized changes in immunity and a predisposition for cancer.

The study reviewed data from 4,437 patients who were diagnosed with lower extremity lymphedema at Mayo Clinic in Rochester from 2000 to 2020. Compared with a matched control group, the group with lymphedema had an increased risk of skin cancer, and for patients who had lymphedema in one leg, that extremity was nearly three times as likely to have skin cancer compared with the other leg.

Lymphedema can be caused by surgery or cancer treatments that remove or damage the lymph nodes, which carry fluids of the immune system. Less commonly, lymphedema can be caused by inherited conditions.

"Patients with lymphedema are not screened routinely by dermatologists, and inadequate screening may lead to delayed diagnosis and treatment," says Afsaneh Alavi, M.D., a Mayo Clinic dermatologist and the study's senior author. "Our findings suggest the need for a relatively high degree of suspicion of skin cancer at sites with lymphedema. There is a need for raising awareness in clinicians seeing patients with lymphedema, and these patients may need regular skin cancer screenings, since early detection of skin cancer is critical."