Role of radiotherapy in residual pineal parenchymal tumors.

Objectives: Surgical excision of pineal parenchymal tumors(PPT), though desirable for good long term outcome, may not always be possible. Role of adjuvant radiotherapy (RT) in residual PPT's is not well delineated. The purpose of this single institutional retrospective study is to assess the role of radiotherapy in residual PPT's.

Patients And Methods: Between 2006-2016, fourteen patients with residual PPT's were treated with adjuvant radiotherapy (12 with 3D conformal RT). Eight had pineocytomas (PC), 4 pineal parenchymal tumors with intermediate differentiation (PPID) and 2 pineoblastomas (PB). Doses of 45-54 Gy was delivered in 1.8-2 Gy per fraction. Cranio-spinal irradiation(CSI) was given to one case of PB and PPID each, with drop lesions at presentation. Patients were followed up at regular intervals.

Results: The average Planning Target Volume (PTV) was 279.4cc. Clinico-radiological response was noted in all with complete disappearance of tumor in 4 patients with PC and 2 with PPID. Delayed recurrence (36-72 months later, median 42.5 months) was seen in 3 patients with PC and early recurrence in both with PB (median 28 months). Overall median follow-up for PC and PB was 54 and 31.5 months respectively. Two patients with PC and 2 with PB expired. The median follow-up for PPID was 21.5 months with no deaths or recurrences.

Conclusions: Some PC and PPID may behave aggressively and recur or spread along neural axes requiring close follow up. Radiotherapy appears to be effective in patients with residual PC, PPID. Re-irradiation or radiosurgery may help in recurrences.