Guidelines for Complications of Cancer Treatment Vol VIII Part B

Highest relative risk of second cancer is in young cancersurvivors and is estimated to be 5.6.Second malignancies after treatment of brain tumour withradiation are meningioma, sarcoma and glioma.Cumulative risk of developing a second brain tumourover the first 10 years after treatment was 1.3% (95%CI 0.4% -3.9%) and over 20 years 1.9% (0.7% -5.0%).Relative risk of second brain tumour compared withincidence in the normal population was 9.38 (3.05 to21.89). Cumulative incidence of brain tumors at 20 yearsafter cranial RT in acute lymphoblastic leukemia (ALL)was 1.39% (95% CI, 0.63%- 2.15%). Thus, secondmalignancy is relatively uncommon after RT in primarybrain tumour.Cerebrovascular accident (CVA)An increased incidence of cerebrovascular accidents (CVA)and related mortality has been reported in patients withpituitary adenoma treated with RT. Possible risk factors includehypopituitarism, irradiation and extensive surgery, but noneare proven causes at present.Brada et al., reported an increased mortality in a seriesof 334 irradiated patients with a 4.1-fold excess of CVAin pituitary tumour. However, increase in CVA may berelated to endocrine dysfunction rather than RT itself.Radiation induced necrosisRT induced necrosis is usually observed in 1-2% after highdose RT.However, RT induced necrosis (‘pseudo-progression’)is increased up to 14% after treatment with concurrentRT and Temozolomide. This increased contrastenhancement after RT is called ‘pseudo-progression’.353