Optimizing radiotherapy schedules for elderly glioblastoma multiforme patients

Hypofractionated radiotherapy for glioblastoma: A large institutional retrospective assessment of 2 approaches

Background

Glioblastoma (GBM) poses therapeutic challenges due to its aggressive nature, particularly for patients with poor functional status and/or advanced disease. Hypofractionated radiotherapy (RT) regimens have demonstrated comparable disease outcomes for this population while allowing treatment to be completed more quickly. Here, we report our institutional outcomes of patients treated with 2 hypofractionated RT regimens: 40 Gy/15fx (3w-RT) and 50 Gy/20fx (4w-RT).

Methods

A single-institution retrospective analysis was conducted of 127 GBM patients who underwent 3w-RT or 4w-RT. Patient characteristics, treatment regimens, and outcomes were analyzed. Univariate and multivariable Cox regression models were used to estimate progression-free survival (PFS) and overall survival (OS). The impact of chemotherapy and RT schedule was explored through subgroup analyses.

Results

Median OS for the entire cohort was 7.7 months. There were no significant differences in PFS or OS between 3w-RT and 4w-RT groups overall. Receipt and timing of temozolomide (TMZ) emerged as the variable most strongly associated with survival, with patients receiving adjuvant-only or concurrent and adjuvant TMZ having significantly improved PFS and OS (P < .001). In a subgroup analysis of patients that did not receive TMZ, patients in the 4w-RT group demonstrated a trend toward improved OS as compared to the 3w-RT group (P = .12).

Conclusions

This study demonstrates comparable survival outcomes between 3w-RT and 4w-RT regimens in GBM patients. Receipt and timing of TMZ were strongly associated with survival outcomes. The potential benefit of dose-escalated hypofractionation for patients not receiving chemotherapy warrants further investigation and emphasizes the importance of personalized treatment approaches.

Newly Diagnosed Glioblastoma in Elderly Patients

Purpose of Review

Elderly patients with newly diagnosed glioblastoma (eGBM) carry a worse prognosis compared with their younger counterparts. eGBM garners special attention due to the unique challenges, including increased treatment-associated toxicity, less relative benefit from aggressive therapy, medical comorbidities, and immunosuppression. The pivotal GBM trials excluded patients > 70 years old and the optimal treatment approach remains unsettled for eGBM. In this review, we analyze the historical evidence-based data for treating eGBM and discuss the future direction for managing this vulnerable population.

Recent Findings

Treatment for eGBM continues to evolve. Therapy choice is guided by performance status and presence of O6-methylguanine-DNA-methyltransferase (MGMT) promoter methylation. For eGBM with good performance status, combinatorial hypofractionated radiation therapy (hRT) and temozolomide should be recommended. For those with poor performance status, further stratification based on MGMT promoter methylation test result is recommended. Single-agent temozolomide is a viable treatment option for MGMT methylated tumors (mMGMT); in particular, those classified with receptor tyrosine kinase II methylation. hRT alone can be considered in MGMT unmethylated (uMGMT) eGBM patients. As precision oncology continues to advance, effective targeted and immunotherapy may emerge as new treatment options for eGBM.

Summary

Management of elderly patients with newly diagnosed GBM carries a unique set of challenges. Progress has been made in defining the optimal therapeutic approach for these patients, but many questions remain to be answered.

Treatment of elderly patients with glioblastoma: from clinical evidence to molecular highlights

Elderly patients with glioblastoma are characterized by a high rate of associated morbidities, and a poor prognosis. Therefore, they have been excluded from most prospective clinical trials. However, the poorer outcome retrospectively reported in these patients might be also related to that those are less likely to receive the appropriate treatment than their younger counterparts. We reviewed the literature with regard to the optimal therapeutic management of this particular population, with focus on molecular perspectives for improving patients' selection. Clinical data have demonstrated that open craniotomy with resection of the tumor was superior to biopsy only in elderly patients with good Karnofsky Performance Status (KPS) score. Then, postoperative radiotherapy (RT) improves survival without impairing functional status or neurocognitive functions, compared with best supportive care only following resection. Despite promising preliminary data, the addition of concomitant temozolomide to RT has not been validated in patients more than 70-years old. In case of additional poor prognostic factors or after biopsy only, there is no definitive demonstration that RT, chemotherapy, or both could improve outcome. Incorporation of more sensitive predictive and/or prognostic molecular factors could help physicians in patients' selection. Further prospective trials should incorporate age-dependent molecular specificities in their design, and better focus on particular subgroup of patients exhibiting specific molecular alterations.

Current developments in the radiotherapy approach to elderly and frail patients with glioblastoma multiforme

The benefit of postoperative radiotherapy (RT) has been demonstrated in elderly patients aged 65 years or older with glioblastoma multiforme. Hypofractionated RT schedules can reduce the time and morbidity of treatment while maintaining comparable survival outcomes to lengthy conventional RT. Current international randomized clinical trials are studying the optimized hypofractionated RT regimens, hypofractionated RT in comparison with temozolomide chemotherapy and hypofractionated RT in comparison with the same RT plus temozolomide. Given the guarded prognosis of the elderly and frail patients, quality of life and side effects of treatment should be closely examined. As more than half of cancers in the world occur in developing countries, hypofractionated RT could be better utilized as a cost-effective treatment for this group of patients.

Glioblastoma in the elderly: the Memorial Sloan-Kettering Cancer Center Experience (1997-2007)

BACKGROUND

Glioblastoma (GBM) is the most common malignant primary brain tumor, and approximately 50% of cases occur in patients aged > or =65 years. However, to the authors' knowledge, there is no accepted standard treatment for elderly GBM patients, and specific prognostic factors in the elderly GBM population have not been systematically studied to date.

METHODS

The Memorial Sloan-Kettering Cancer Center institutional database was used to identify patients with histologically confirmed GBM who were aged > or =65 years at the time of diagnosis.

RESULTS

Three hundred ninety-four GBM patients with a median age of 71.9 years (59% of whom were men) were included. Approximately 18% of patients underwent biopsy, whereas 82% underwent tumor resection; 81% received radiotherapy (RT), and 43% received adjuvant chemotherapy. The median overall survival was 8.6 months; at the time of last follow-up, 90% of patients had died, and the median follow-up of the 39 surviving patients was 12 months. In a multivariate analysis, younger age, better Karnofsky performance status (KPS), single tumor, and surgical resection were found to be independent predictors of survival. Comparing 103 patients who received adjuvant chemotherapy with 48 who were only followed after RT, there was a 55% decrease in the risk of death (hazards ratio, 0.45; 95% confidence interval, 0.30-0.66 [P < .0001]) after adjusting for age, KPS, extent of surgical resection, and number of lesions.

CONCLUSIONS

Similar to studies in younger GBM patients, advancing age, KPS, and extent of tumor resection were found to be independent prognostic factors in the current study. Although survival is inferior in older GBM patients, age alone should not disqualify patients from aggressive therapy with surgical resection, RT, and chemotherapy.

[Is geriatric assessment adapted to radiotherapy?]

Cancer in the elderly represents a major public health topic and its importance will increase in the future because of increased life expectancy and ageing. Cancer prognosis is worse due to late diagnosis, frequent comorbidities and treatment often considered as suboptimal. Reference treatments were primarily validated for younger or selected elderly patients and experimental data collected on most vulnerable are rare. Oncogeriatrics development for 15 years made it possible to consider two fundamental aspects, which are the geriatric evaluation, from the most simple to the complete one, and the development of specific trials. In addition, a strong institutional policy allowed promotion, on the French national territory, of regional experiments thanks to Pilot Units of Oncogeriatrics Coordination (UPCOG). The question of the interest of a geriatric evaluation in radiotherapy is related mainly to the difficulties of tolerance and observance of this treatment, but also with its effectiveness and this review explores the main curative, adjuvant and palliative indications as well as research perspectives.