Sarcoidosis in Sarcoma Patients May Be More Common Than Realized, Study Finds

The occurrence of sarcoidosis and sarcoma — a rare type of cancer — at the same time or one after the other may be more common than previously thought, according to a small study.

These results highlight a potential association between these two distinct diseases, which could change clinical practice.

The study, “A nonrandom association of sarcoidosis in patients with gastrointestinal stromal tumor and other sarcomas,” was published in the journal Rare Tumors.

Sarcoidosis-related chronic inflammation leads to the formation of small abnormal lumps or nodules — called granulomas — in several organs of the body, but most commonly in the lungs and lymph nodes.

Several studies have suggested that patients with sarcoidosis have a two-fold increased risk of developing cancer. On the other hand, sarcoidosis has also been reported to occur after cancer diagnosis, and to be associated with cancer relapse or the development of a secondary cancer in more than half of those patients.

While some cases of concurrent sarcoidosis and sarcoma — a type of cancer that grows in the body’s connecting and supporting tissues — have been reported, a potential association between these two conditions remains undetermined.

Since sarcoidosis usually causes nodules in the lungs, and sarcomas most commonly spread to that organ, finding an association between the two conditions could prevent the misdiagnosis of lung nodules as metastatic sarcoma — when the cancer spreads.

Now researchers at the University of Miami Miller School of Medicine have reported a series of eight patients diagnosed with both sarcoma and sarcoidosis between 2007 and 2016 at the Sylvester Comprehensive Cancer Center in Miami.

The team analyzed the clinical data of the six women — three Caucasians, two African-Americans, and one Hispanic — and two Caucasian men diagnosed with both conditions.

Five patients had sarcoma in the gut walls — one of the most common types of sarcoma — and the remaining three had sarcoma in the soft tissues of the hands, uterus, or arms/legs. Sarcoidosis affected the lungs of seven patients, and the abdominal lymph nodes and spleen of one patient.

Four patients were diagnosed with sarcoidosis after an average of 16 months following sarcoma diagnosis, three several years before sarcoma, and one at the same time as sarcoma diagnosis.

Additional analysis on the estimated frequency of both sarcoidosis and sarcoma showed that the estimated risk of having both diseases was significantly higher than expected.

According to the team, “the expected number of patients with both sarcoma and sarcoidosis is 2.6 for the state of Florida. … Assuming all sarcoma patients in the state of Florida were to be seen at our center, the estimated risk of having sarcoma and sarcoidosis was significantly higher than expected, indicating the probability of coexistence of these two entities is 205% higher than expected.”

These results therefore suggest a nonrandom association between sarcoidosis and sarcoma.

“Moreover, our results likely underestimate the association as we are likely missing patients with occult sarcoidosis not detected on routine imaging as well as the fact our center does not see all sarcoma patients in our state nor in our catchment area,” the researchers wrote.

Despite the small size of the study, the team believes the results reveal the possibility that lung nodules in sarcoma patients could be sarcoidosis-related, rather than sarcoma metastasis, and that in these patients, lung nodules should be analyzed to clarify their origin.

“This case series points to a statistically robust, nonrandom association between sarcoma and sarcoidosis that has not been previously described. Presumed metastatic sarcoma should be considered for biopsy particularly with demographic characteristics or imaging features suggestive of sarcoidosis,” the researchers wrote.

This change in clinical practice could be crucial to implementing appropriate treatment and preventing disease progression.

Additionally, the researchers noted that some evidence suggests that activation of tumor-related molecules may induce sarcoma-related sarcoidosis, highlighting the need for additional studies on the molecular mechanisms of sarcoidosis.