Second Primary Malignancies in Patients with Well-differentiated/Dedifferentiated Liposarcoma.

Background: Well-differentiated/dedifferentiated (WD/DD) liposarcoma is a rare malignancy of putative adipocyte origin. To our knowledge, there have only been isolated case reports describing second primary cancer in patients with this disease. We report on a combined case series of such patients and explore the frequency of this occurrence using a national cancer database.

Materials And Methods: Demographics and clinicopathological data were collected from patients with WD/DD liposarcoma who were found to have a concurrent or subsequent second primary cancer, at one of three sarcoma referral centers from 2014-2016. The Surveillance, Epidemiology and End Results (SEER) database was also queried to identify adult patients diagnosed with WD/DD liposarcoma between 1973-2012. Observed/expected (O/E) ratios of second primary malignancies among these cases were calculated by comparison to the age-adjusted cancer incidence in the general population using SEER*stat software.

Results: In total, 26 out of 312 consecutive patients (8.3%) with WD/DD liposarcoma at our centers had a second primary cancer identified within 2 years of liposarcoma diagnosis. In the SEER database, among 1,845 patients with WD/DD liposarcoma, 75 (4.1%) had a second cancer within 2 years after liposarcoma diagnosis (O/E ratio=1.81, 99% confidence interval(CI)=1.33-2.40). Patients less than 50 years old at the time of liposarcoma diagnosis had a higher O/E ratio for second primary malignancy compared to older patients. A total of 269 patients (14.6%) developed a second cancer (O/E=1.33, 99% CI=1.15-1.54).

Conclusion: In some patients with WD/DD liposarcoma, there appears to be an increased risk of having a second primary cancer. Further validation and investigation is needed, as this finding may have implications (e.g. closer screening) for patients with this disease.