2ND CANCERS AFTER MEDULLOBLASTOMA - POPULATION-BASED RESULTS FROM THEUNITED-STATES AND SWEDEN

Medulloblastoma, one of the most common central nervous system (CNS) t umors in children, requires aggressive multimodality therapy including surgery, radiation therapy, and occasionally chemotherapy. Given its intensive treatment regimen and improved survival during the past 20 y ears, it is likely that a cohort of survivors will result who may incu r consequences of therapy, including a second cancer. We used populati on-based data from the United States and Sweden to estimate risks of s econd neoplasms in patients with histologically confirmed medulloblast oma (n = 1,262). Overall, there was a 5.4-fold excess of second neopla sms (95 percent confidence interval = 3.3-8.4) based on 20 observed an d 3.7 expected cancers. The second cancers occurred eight to 432 month s after initial diagnosis (median, 73 months) with significantly eleva ted ratios for all intervals examined except for less than one year af ter initial diagnosis. Significantly elevated risks were seen for canc ers of the salivary glands, cervix uteri, brain and CNS, thyroid gland , and acute lymphoblastic leukemia. Of the 15 second cancers with trea tment data, seven occurred in the radiation field or within areas of s catter while two others may have been radiation-related. Although base d on small numbers of second cancers, the results suggest that as surv ival increases, some patients with medulloblastoma will have an increa sed risk of a second cancer, particularly a radiation-related cancer. Thus, as survival improves, late-occurring consequences of diagnosis a nd treatment will need to be carefully assessed. Identification of pat ients hypersensitive to radiation therapy, such as those with Gorlin S yndrome, should also be attempted in order to reduce the sequelae from intensive radiation exposure.