Sirolimus protects organ-transplant recipients against developing skin cancer, reducing their risk by 40%, according to a retrospective cohort study published in JAMA Dermatology on Jan. 20.
Recipients of solid organs are at three- to fourfold higher risk of developing cancer, compared with the general population, and the most common type they get is nonmelanoma skin cancer. The risk of developing cutaneous squamous cell carcinoma is 65-250 times higher in organ-transplant recipients. Drugs that reduce the growth and proliferation of tumor cells by inhibiting mTOR (mammalian target of rapamycin), including sirolimus, are believed to reduce this cancer risk, said Pritesh S. Karia of the department of dermatology, Brigham and Women’s Hospital and Harvard University, Boston, and his associates (JAMA Dermatol. 2016 Jan 20. doi: 10.1001/jamadermatol.2015.5548).
The investigators reviewed the electronic medical records of 329 patients (mean age, 56 years) who underwent organ transplantation at one of the two medical centers during a 9-year period and who then developed a cancer of any type. The study participants received renal (53.8%), heart (17.6%), lung (16.4%), liver (10.3%), or mixed-organ (1.8%) transplants. The most common index cancers they developed post transplant included cutaneous squamous cell carcinoma (31.9%), basal cell carcinoma (22.5%), and melanoma (2.7%).
Of the 329 patients, 97 (29.5%) then received sirolimus, while 232 (70.5%) did not. During a median follow-up of 38 months, 130 of these patients (39.5%) developed a second posttransplant cancer. The sirolimus-treated group showed a reduction in risk for cancer of any type, compared with the group that did not receive sirolimus (30.9% of 97 vs. 43.1% of 232).
Nearly all (88.5%) of the second posttransplant cancers that developed were skin cancers, and sirolimus reduced the risk of skin cancers by 40%. The 1-year, 3-year, and 5-year rates of skin cancer after an index posttransplant cancer were 9.3%, 20.6%, and 24.7% in the sirolimus group, compared with 17.7%, 31.0%, and 35.8%, respectively, in the untreated group, “thus demonstrating a lower risk for skin cancer with sirolimus treatment,” they said.
“Even for patients who have already had difficulty with skin cancer formation, mTOR inhibition appears to be of benefit. No difference in cancer outcomes was observable between sirolimus-treated and [untreated] groups because poor outcomes were rare,” Mr. Karia and his associates wrote.
These findings suggest that sirolimus chemoprevention should be considered for the subset of organ-transplant recipients who develop post-transplant cancer, they noted. The results also highlight the need for dermatologists and transplant physicians “to be aware of skin cancer history, coordinate regular posttransplant surveillance of skin cancers” in patients with organ transplant recipients, especially those with a history of skin cancer, and to communicate closely “as skin cancers form to consider reduction in immunosuppressive therapy or conversion to an mTOR-based regimen if skin cancer formation is of concern,” they added.
This study was supported by sirolimus manufacturer Novartis Pharmaceuticals. Mr. Karia and his associates reported having no relevant financial disclosures.