The results of a new study found that patients receiving chemotherapy and radiation therapy simultaneously for abdominopelvic cancers were at higher risk of developing secondary sarcoma compared with patients who received surgery or radiation therapy alone for their treatment.
"To our knowledge, this is the largest and most comprehensive series to estimate the risk of secondary sarcoma in a large group of adult patients treated for multiple primary abdominopelvic cancers," write the investigators, led by first author Amanda E. Hird, MD, a urology resident at the University of Toronto Temerty Faculty of Medicine, and senior author Robert K. Nam, MD, Head of Genitourinary Oncology at Sunnybrook Health Sciences Centre in Toronto, in their article for JAMA Network Open. "Large population-based studies in the United States among men with prostate cancer and women with endometrial cancer have demonstrated an increased risk of a second solid tumor of any type among those treated with radiation."
From January 1, 2002, to January 31, 2017, Dr. Hird and colleagues evaluated the risk of developing secondary sarcoma in 173,580 patients diagnosed with nonmetastatic cancer of the prostate, cervix, bladder, colon, rectum or anus, uterus, or testis. Some patients were treated with chemotherapy, radiation therapy, or surgery alone, while others received a chemotherapy and radiation therapy combination, and a final group received all 3 treatments. Over half of the population was diagnosed with genitourinary cancer (51.4%).
Surgery alone was the most common treatment (37.1%), followed by radiation alone (29.5%), radiation with chemotherapy (9.0%), radiation with surgery (8.8%), and all 3 treatments (6.8%). After a median follow-up of 5.7 years, the incidence of sarcoma was 0.2% among all patients in the study. Compared with a reference group of patients who underwent surgery only, those who received a combination of chemotherapy and radiation had the greatest risk for developing secondary sarcomas, with a cause-specific relative hazard (csRH) of 4.07, followed by radiation alone (csRH of 2.35), radiation with surgery (2.33), and all 3 treatments combined (2.27).
"We hypothesize that this increase in the rate of sarcoma is secondary to patients living longer after radiation therapy exposure," conclude Dr. Hird and colleagues. "Because the number of sarcoma cases did not increase in the surgery group, this increase may reflect improvements in overall cancer-specific survival after radiation therapy treatment, allowing for more sarcomas to develop in patients with radiation exposure. It may also be possible that the emergence of complex radiation therapy treatment modalities may place patients at an increased risk of developing secondary cancer."
For More Information
Hird A, Magee D, Matta R, et al (2020). Assessment of secondary sarcomas among patients with cancer of the abdomen or pelvis who received combinations of surgery, radiation, and chemotherapy vs surgery alone. JAMA Netw Open, 3(10):e2013929. DOI:10.1001/jamanetworkopen.2020.13929
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