Importance of the mini-mental status examination in the treatment of patients with brain metastases: a report from the Radiation Therapy Oncology Group protocol 91-04

Abstract

Purpose: Little information is available on the importance of pretreatment Mini-Mental Status Exam (MMSE) on long-term survival and neurologic function following treatment for unresectable brain metastases. This study examines the importance of the MMSE in predicting outcome in a group of patients treated with an accelerated fractionation regimen of 30 Gy in 10 daily fractions in 2 weeks.

Materials and methods: The Radiation Therapy Oncology Group (RTOG) accrued 445 patients to a Phase III comparison of accelerated hyperfractionated (AH) radiotherapy (1.6 Gy b.i.d.) to a total dose of 54.4 Gy vs. an accelerated fractionation (AF) of 30 Gy in 10 daily fractions from 1991 through 1995. All patients had histologic proof of malignancy at the primary site. Brain metastases were measurable by CT or MRI scan and all patients had a Karnofsky performance score (KPS) of at least 70 and a neurologic function classification of 1 or 2. Two hundred twenty-four patients were entered on the accelerated fractionated arm, and 182 were eligible for analysis (7 patients were judged ineligible, no MMSE information in 29, no survival data in 1, no forms submitted in 1).

Results: Average age was 60 years; 58% were male and 25% had a single intracranial lesion on their pretherapy evaluation. KPS was 70 in 32%, 80 in 31%, 90 in 29%, and 100 in 14%. The average MMSE was 26.5, which is the lower quartile for normal in the U.S. population. The range of the MMSE scores was 11-30 with 30 being the maximum. A score of less than 23 indicates possible dementia, which occurred in 16% of the patients prior to treatment. The median time from diagnosis to treatment was 5 days (range, 0-158 days). The median survival was 4.2 months with a 95% confidence interval of 3.7-5.1 months. Thirty-seven percent of the patients were alive at 6 months, and 17% were alive at 1 year. The following variables were examined in a Cox proportional-hazards model to determine their prognostic value for overall survival: age, gender, KPS, baseline MMSE, time until MMSE below 23, time since diagnosis, number of brain metastases, and radiosurgery eligibility. In all Cox model analyses, age, KPS, baseline MMSE, time until MMSE below 23, and time since diagnosis were treated as continuous variables. Statistically significant factors for survival were pretreatment MMSE (p = 0.0002), and KPS (p = 0.02). Age was of borderline significance (p = 0.065) as well as gender (p = 0.074). A poorer outcome is associated with an increasing age, male gender, lower MMSE, and shorter time until MMSE below 23. Improvement in MMSE over time was assessed; 62 patients died prior to obtaining follow-up MMSE, and 30 patients had a baseline MMSE of 30 (the maximum), and, therefore, no improvement could be expected. Of the remaining 88, 48 (54.5%) demonstrated an improvement in their MMSE at any follow-up visit. Lack of decline of MMSE below 23 was seen in long-term survivors, with 81% at 6 months and 66% at 1 year of patients maintaining a MMSE above 23. Analysis of time until death from brain metastases demonstrated that decreasing baseline MMSE (p = 0.003) and primary site (breast vs. lung vs. other p = 0.032) were highly associated with a terminal event.

Conclusion: While gender and perhaps age remain significant predictors for survival, MMSE is also an important way of assessing a patient's outcome. Accelerated fractionation used in the treatment of brain metastases (30 Gy in 10 fractions) appears to also be associated with an improvement in MMSE and a lack of decline of MMSE below 23 in long-term survivors.