A graded prognostic model for patients surviving 3 years or more (GPM ≥ 3Ys) after stereotactic radiosurgery for brain metastasis

Yasunori Sato; Masaaki Yamamoto; Toru Serizawa; Kei-Ichiro Yamada; Yoshinori Higuchi; Hidetoshi Kasuya

doi:10.1016/j.radonc.2020.11.024

A graded prognostic model for patients surviving 3 years or more (GPM ≥ 3Ys) after stereotactic radiosurgery for brain metastasis

Radiother Oncol. 2021 Mar:156:29-35. doi: 10.1016/j.radonc.2020.11.024. Epub 2020 Nov 27.

Authors

Yasunori Sato¹, Masaaki Yamamoto², Toru Serizawa³, Kei-Ichiro Yamada⁴, Yoshinori Higuchi⁵, Hidetoshi Kasuya⁶

Affiliations

¹ Department of Preventive Medicine and Public Health, Keio University School of Medicine, Tokyo, Japan.
² Katsuta Hospital Mito GammaHouse, Hitachi-naka, Japan; Department of Neurosurgery, Tokyo Women's Medical University Medical Center East, Japan. Electronic address: BCD06275@nifty.com.
³ Tokyo Gamma Unit Center, Tsukiji Neurological Clinic, Tokyo, Japan.
⁴ Keio University School of Medicine, Tokyo, Japan.
⁵ Department of Neurological Surgery, Chiba University Graduate School of Medicine, Japan.
⁶ Department of Neurosurgery, Tokyo Women's Medical University Medical Center East, Japan.

PMID: 33249092
DOI: 10.1016/j.radonc.2020.11.024

Abstract

Background and purpose: As more cancer patients with brain metastases (BMs) are surviving longer due to recent advancements in various treatment modalities, we developed a grading system for stereotactic radiosurgery (SRS)-treated BM patients with long survival. This is a Graded Prognostic Model for Patients Surviving 3 Years or More (GPM ≥ 3Ys).

Materials and methods: First, using clinical factor-survival time analysis of 3237 patients in whom gamma knife (GK) SRS was performed by the second author (test cohort), we developed the GPM ≥ 3Ys based on survival ≥3 years as the objective variable. The validity of this model was then tested using another series of 3317 patients independently undergoing GK SRS performed by the third author (verification cohort). Number of patients surviving 3 years or more were 289 (8.9%) and 348 (10.5%), respectively.

Results: Using the test series, among various pre-SRS clinical factors, noted below, five were shown to be highly correlated with survival of ≥3 years. Therefore, we assigned scores for these five factors, i.e., "tumor numbers 1/2-4/≥5 (score; 6/1/0)", "female/male (5/0)", "KPS ≥80%/<80% (5/0)", "primary cancers of breast/lung/gastrointestinal tract/other (score; 1/0/3/0)", "controlled primary cancer/not (8/0)" and "existing extra-cerebral metastases/not (5/0). Patients were categorized into four grades according to the sum of scores, i.e., 0-9, 10-19, 20-29 and 30-36. Post-SRS mean survival times (MSTs) differed significantly (p < 0.0001) with no overlapping of 95% confidence intervals (CIs) among the four grades. Also, in the verification series, MSTs differed significantly (p < 0.0001) with no overlapping of 95% CI among the four grades of the GPM ≥ 3Ys system.

Conclusion: Although this was a retrospective study, the GPM ≥ 3Ys system was shown to be very useful to physicians selecting among more aggressive treatment modalities for patients in whom longer survival can be expected.

Keywords: Brain metastases; Gamma knife; Grading system; Prognosis; Radiation therapy; Radiosurgery.

MeSH terms

Brain Neoplasms* / radiotherapy
Brain Neoplasms* / surgery
Female
Humans
Male
Prognosis
Radiosurgery*
Retrospective Studies
Survival Rate