Evaluation of outcome and prognostic factors in thoracic primitive neuroectodermal tumor: a study of 84 cases.

Background: Data on thoracic primitive neuroectodermal tumor (PNET) treated with a uniform chemotherapy protocol are minimal in the literature. We analyzed patients with thoracic PNET for outcome and prognostic factors.

Methods: This is a single-institutional data review of patients treated between June 2003 and November 2011 with uniform neoadjuvant chemotherapy, surgical intervention, or radiotherapy (RT), or a combination of these treatments as local therapy followed by adjuvant chemotherapy.

Results: Thoracic PNET was found in 84 of 374 (22%) patients with PNET with a median age of 15 years (range, 3-40 years); 27 (32%) of these patients had metastases. Thirty patients underwent surgical resection; 27 patients received radical RT after neoadjuvant chemotherapy. The radical RT group did not have adverse tumor characteristics or poor response to neoadjuvant chemotherapy. At median follow-up of 20.8 months (range, 2-104.6 months), 5-year event-free survival (EFS), overall survival (OS), and local control rate (LCR) were 24.4% ± 5.9%, 47.9% ± 8.4%, and 59.3% ± 9%, respectively, for the entire cohort, and 31% ± 7.7%, 59% ± 10.4%, and 67% ± 9.7%, respectively, for the group with localized tumors. In multivariate analysis, symptom duration longer than 4 months (p = 0.03), primary tumor of skeletal origin (p = 0.03), and radical RT (p = 0.006) predicted inferior EFS in the entire cohort and those with localized disease; metastatic disease (p = 0.002) predicted inferior OS. Radical RT predicted inferior LCR in the entire cohort and the group with localized tumor; tumor diameter larger than 8 cm (p = 0.02) and symptom duration longer than 4 months (p = 0.02) predicted inferior LCR in the group with localized tumor.

Conclusions: This is a single-institutional experience of 84 patients with thoracic PNETs who underwent a uniform chemotherapy protocol. Novel prognostic factors were identified for thoracic PNET. All efforts should be made to resect primary tumor after neoadjuvant chemotherapy because radical RT results in inferior EFS and LCR despite good response to neoadjuvant chemotherapy.