Markedly Elevated Sarcoma Risk in Long-Term Survivors of Hereditary Retinoblastoma

By Will Boggs MD

November 26, 2019

NEW YORK (Reuters Health) - The risk of bone and soft-tissue sarcoma is markedly elevated in long-term survivors of hereditary retinoblastoma treated with radiation, researchers report.

"We provide novel data that after radiotherapy for hereditary retinoblastoma, if sarcoma develops, it occurs in distinctive patterns by the type of sarcoma and location on the body," Dr. Lindsay M. Morton of the National Cancer Institute, in Bethesda, Maryland, told Reuters Health by email. "These findings provide a potential roadmap for tailoring the screening approach for sarcomas among retinoblastoma survivors."

Radiotherapy is an established cause of sarcoma after hereditary retinoblastoma, but little is known about the long-term risk of sarcoma after hereditary retinoblastoma and whether the risks varied by specific tumor characteristics.

Dr. Morton and colleagues used data from 952 irradiated survivors of hereditary retinoblastoma who were originally diagnosed between 1914 and 2006 to quantify sarcoma risk and to analyze risk factors by anatomic location and histologic subtype.

Nearly half of the patients (44%) were also treated with chemotherapy. The median age at sarcoma diagnosis was 15.5 years for bone sarcomas and 33.5 years for soft-tissue sarcomas.

Compared with the general population, these survivors had a more than 2,000 times increased risk of bone sarcomas in the head and neck and a 169-fold increased risk of bone sarcomas in the body and extremities (with 21.7 and 12.0 cases per 10,000 person-years, respectively).

In contrast to patterns in the general population, the risk of bone sarcoma in these survivors decreased with increasing age, the researchers report in the Journal of Clinical Oncology, online October 17.

For head and neck bone sarcomas, the cumulative incidence rose sharply after age 5 years through adolescence and then increased more modestly through 60 years after retinoblastoma. For body and extremity bone sarcomas, the cumulative incidence also increased sharply after age 5 through adolescence but remained stable thereafter.

The risk of soft-tissue sarcoma in the head and neck was 542 times greater in hereditary retinoblastoma survivors than in the general public and was 45.7-fold greater for other regions of the body (with 25.0 and 11.9 cases per 10,000 person-years, respectively).

The risk of body and extremity soft-tissue sarcoma increased substantially with increasing age, but there was no association between attained age for head and neck soft-tissue sarcomas.

In cumulative-incidence analyses, the incidence of head and neck soft-tissue sarcoma rose steadily throughout the entire duration of follow-up, whereas soft-tissue sarcoma in other body regions rarely occurred before the fourth decade of life, at which point the incidence increased steeply.

Patients diagnosed before age 12 months had the highest risks for head and neck soft-tissue sarcoma, whereas age at diagnosis was not associated with the risk of body and extremity soft-tissue sarcoma.

Females were 41% less likely than males to be diagnosed with head and neck soft-tissue sarcoma, but they were twice as likely as males to be diagnosed with body and extremity soft-tissue sarcoma.

Use of chemotherapy, family history of retinoblastoma, and year of retinoblastoma diagnosis did not appear to influence the risk of either bone or soft-tissue sarcoma.

"This report should inform study design in assessing the efficacy of sarcoma screening in this high-risk population," Dr. Morton said. "For example, our data suggest that screening for bone sarcomas in the head should persist for decades following retinoblastoma because of persistently elevated risks, whereas screening for bone sarcomas in the extremities may no longer be needed after adolescence."

"Because no evidence-based screening protocols have been developed for retinoblastoma survivors to date, international collaboration will be essential for advancing research to optimize the long-term health and clinical care for these patients," she said.

SOURCE: https://bit.ly/37qQHB6

J Clin Oncol 2019.

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