Stereotactic radiosurgery alone for small cell lung cancer: a neurocognitivebenefit?

Abstract

Yomo and Hayashi reported results of stereotactic radiosurgery alone for brainmetastases from small cell lung cancer. This strategy aims to avoid theneurocognitive effects of whole-brain radiation therapy. However, radiosurgeryalone increases the risk of distant intracranial relapse, which canindependently worsen cognition. This concern is heightened in histologies likesmall cell with high predilection for intracranial spread. The majority of studypatients developed new brain disease, suggesting radiosurgery alone may not bean optimal strategy for preserving neurocognitive function in this population.We suggest whole-brain radiation therapy should remain the standard of care forsmall cell lung cancer.

Correspondence/Findings

Letter to the Editor:

Yomo and Hayashi recently reported in Radiation Oncology their experiencewith upfront stereotactic radiosurgery (SRS) for brain metastases from small celllung cancer (SCLC) [1]. The authors should be commended for this novel investigation. We agreethat SRS might play a role in SCLC, particularly for treating a limited number ofbrain metastases after prior prophylactic cranial irradiation or prior whole-brainradiation therapy (WBRT). However, we echo the authors’ call for caution inadopting SRS alone as the initial approach for intracranial disease.

The strategy of upfront SRS is gaining increasing prominence [2], spurred by the excellent local control achieved with radiosurgery and byconcerns about the side effects of WBRT. These concerns are bolstered by studiesshowing declines in neurocognition and quality of life in patients receiving WBRT [3–5]. On the other hand, increased intracranial tumor burden often drivescognitive dysfunction [6, 7], and a recognized downside of SRS alone is high rates of distant brainrelapse. This concern is heightened in SCLC, a biologically aggressive tumor whichdisseminates to the central nervous system in approximately two-thirds of patientsduring the course of their disease [8]. Yomo and Hayashi report that 20 of 41 patients (49%) developed new brainmetastases after initial SRS, and because follow-up imaging was available in only 34cases, this rate could be interpreted as 20 of 34 (59%). The overall outcomes fromthis study suggest that radiosurgery may be a reasonable modality in well-selectedpatients with SCLC. However, it is also possible that in populations with high ratesof intracranial relapse, an SRS approach might actually hinder – rather thanhelp – cognitive function.

Which is more important for preserving neurocognition: limiting the volume ofirradiated brain or maximizing intracranial tumor control? The answer is uncertain,and ongoing studies aim to resolve this question (e.g. NAGKC 12–01 testingWBRT versus SRS alone for five or more brain metastases and NCCTG N107C testing WBRTversus SRS following surgical resection of a brain metastasis). Should these trialsfavor SRS, we anticipate increased enthusiasm for radiosurgery in all tumorhistologies – including SCLC – and Yomo and Hayashi’s study willbe an important initial report in this population. In the meantime, however, wesuggest that WBRT remain the standard of care for patients with brain metastasesfrom SCLC.

Author information

MAB is Chief of the Central Nervous System Service and CBS 2nd is Chief of theThoracic Service in the Department of Radiation Oncology.