Current approaches for prophylactic cranial irradiation in extrapulmonary small cell carcinoma.

BACKGROUND: Small cell lung cancer (SCLC) patients, who have achieved complete or partial response after chemotherapy, should be followed with prophylactic cranial irradiation (PCI). PCI for extrapulmonary small cell carcinoma (EPSCC) is not routinely recommended. The purpose of this review is to discuss all aspects of PCI in management of EPSCC. SCOPE: The PubMed database and the database of online abstracts of the American Society of Oncology (ASCO), ASCO Genitourinary (GU) Cancers meetings and clinical trials were searched up to 15 October 2013 using the following search keywords: 'SCC or EPSCC of each organ site and prophylactic cranial radiotherapy'. The language of screened abstracts and manuscripts was limited to English. The papers which included the largest case series and data of cases about prophylactic cranial radiotherapy and/or were published in the last 10 years were selected.
FINDINGS: Many single center studies showed low incidence of brain metastasis in patients with esophageal small cell carcinoma (SCC). Due to the low incidence of brain metastasis, PCI is not recommended for esophageal SCC. Genitourinary, colorectal, small bowel and appendix cranial metastatic SCCs are extremely rare. Therefore, PCI is not recommended. The frequency of brain metastasis of prostate small cell carcinoma is much higher (16-19%) compared to other counterparts of EPSCC. PCI can be performed in selected cases of prostate SCC. High rates (41%) of brain metastasis develop in head and neck SCC. PCI should be considered for patients with head neck SCC.
CONCLUSION: In the literature, the brain metastasis incidence of EPSCC might vary from 1.7% up to 40%. In many patients with ESPCC, PCI is not recommended. However, we have to keep in mind that primary head and neck and prostate SCC are exceptions due to the high incidence of cranial metastasis; PCI should be recommended for these patients on an individual basis.