A new analysis has found that adolescents and young adults who develop thyroid cancer as a secondary cancer have a significantly greater risk of dying than those with primary thyroid cancer. The findings stress the importance of screening young cancer survivors to detect early signs of a potentially life-threatening thyroid malignancy.

Thyroid cancer is one of the five most common malignancies in adolescent and young adult patients (15 to 39 years). It can develop as an initial cancer or, rarely, after treatment for a previous cancer.

Melanie Goldfarb, MD, and David Freyer, DO, of the Keck School of Medicine of the University of Southern California and Children’s Hospital Los Angeles, designed a study to compare the tumor characteristics, treatment, and survival of such primary versus secondary thyroid cancers in adolescent and young adult patients. The results were published in Cancer (2014; doi:10.1002/cncr.28463).

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Their analysis included all adolescent and young adult thyroid cancer cases that were documented in the American College of Surgeons National Cancer Database between 1998 and 2010. Of 41,062 cases, 1,349 (3.3%) had experienced a prior malignancy.

Compared with cases of primary thyroid cancer, cases of secondary thyroid cancer were more likely to be small but to occur in more than one location. Also, patients with secondary thyroid cancer were more than 6.6-times as likely to die as patients with primary cancer, though survival with treatment is excellent for both at greater than 95%. This study suggests that there may be differences between thyroid cancers seen with or without a prior malignancy.

“This study will hopefully spur future research that will investigate if there are any causes—biologic, environmental, prior treatment-related, or access to care disparities—to account for the survival differences in these secondary cancers,” said Goldfarb.

The authors considered whether the current screening guidelines for survivors of childhood cancer would detect these smaller cancers. Freyer noted that the results may have implications for thyroid cancer screening in young cancer survivors.