“However, some features appear to make it less likely that some myositis patients will develop cancer,” said Dr. Miller. Patients with anti-Jo1 antibodies; those with arthritis, arthralgia, interstitial lung disease or Raynaud’s phenomenon; or with autoantibodies to extractable nuclear antigens of any type may be less likely to develop malignancies.
Rheumatologists should carefully evaluate adults with myositis with hallmark risk factors in order to rule out cancer as the cause of some of those symptoms. Screening methods include a careful medical history; physical examination; general laboratory screening; chest X-ray; stool hemoccult three times annually; a prostate exam and prostate-specific antigen testing in males; and a careful gynecological examination, pap smear and mammography in females, Dr. Miller said. In female myositis patients, rheumatologists should also consider transvaginal sonography and testing for cancer antigen 125 (CA-125). Of course, it’s important to take individual cancer risk factors, such as smoking or family history of cancer, into account, too, when choosing screening evaluations, he said.
If cancer is confirmed, a clinician’s immediate therapeutic focus should be on the malignancy, said Dr. Miller, since “if you can completely resolve the cancer, in some cases you can completely resolve the myositis.”
Scleroderma Raises Risk
A systemic sclerosis (scleroderma) diagnosis may also raise a patient’s risk of cancer, particularly lung, bladder in females, hematologic, liver and nonmelanoma skin cancer in males, said Dr. Shah. In the Johns Hopkins Scleroderma Center cohort, about 12% of patients have a history of malignancy, she said. Cancer is a major nonscleroderma cause of death in systemic sclerosis patients.
Scleroderma patients with diffuse disease, those who are older at the first clinical signs of systemic sclerosis, patients with prior immunosuppressant use or chronic inflammation and organ damage may have a higher risk of malignancy, Dr. Shah said. Often, patients develop both systemic sclerosis and cancer within a close interval of each other, similar to dermatomyositis, she said. This has been commonly noted with breast cancer, but has also been observed with other tumor types.
‘It is our responsibility as rheumatologists to include cancer screening as part of our practice.’
Possible explanations for this temporal link between cancer and the onset of autoimmunity include the use of cytotoxic therapies (to treat cancer or scleroderma) or radiation therapy for cancer, a shared genetic susceptibility for both cancer and autoimmunity, commonly inciting environmental exposures or the possibility that systemic sclerosis is paraneoplastic, Dr. Shah said.
