Prognostic factors and survival in primary malignant astrocytomas of the spinal cord: a population-based analysis from 1973 to 2007

Abstract

Study design: Observational cross-sectional study.

Objective: Using data from the population-based cancer registries of the Surveillance, Epidemiology and End Results (SEER) program, we analyzed demographic features, tumor and treatment characteristics, as well as survival rates in patients with primary malignant astrocytomas of the spinal cord (PMASC).

Summary of background data: PMASC is a rare neoplasm and is considered to carry the same dismal outcome as their cerebral counterparts. Our current knowledge is incomplete, and understanding the epidemiology, diagnosis, and optimal treatment still poses challenges.

Methods: The SEER data from 1973 to 2007 were reviewed for pathologically confirmed primary anaplastic astrocytomas (AA) and glioblastomas of the spinal cord (C72.0). We compared the clinical features and outcomes of the cohort in uni- and multivariate fashion. Survival was calculated and compared using Kaplan-Meier curves and log-rank analysis.

Results: Our search criteria retrieved 135 patients diagnosed with PMASC. The median survival for PMASC was 13 months with 1-, 2-, and 5-year survival rates of 51.8%, 32.2%, and 18.7%. Patient diagnosed with AA had a median survival time of 17 months versus 10 months in patients diagnosed with glioblastomas. Adult patients observed markedly prolonged survival compared with the pediatric group, with a 16-month versus 9-month median survival, respectively. Multivariate analysis revealed age at diagnosis, pediatric and adult age groups, sex, tumor histology, and extent of resection as significant predictors of survival. Interestingly, outcomes did not significantly change throughout the last decades or by receiving radiotherapy.

Conclusion: Outcome for patients diagnosed with PMASC remains poor and presents an ongoing challenge for professionals in the field of neurospinal medicine and surgery. In our analyses of AA, adult patients, males, and patients undergoing radical resections were associated with increased survival. However, incidence of these lesions is low; hence, building strong collaborative, interdisciplinary, and multi-institutional study groups is necessary to define the optimal treatment of PMASC.

Figure 1. Kaplan-Meier curve: entire cohort of PMASC patients

Kaplan–Meier plot of survival for the entire cohort of patients with PMASC (n=135). Median (mean) survival was 13 (69.7) months, 6 months and 1-, 2-, 5-, 10-year survival rates were 72.3%, 51.8%, 32.2%, 18.7%, and 13.8%, respectively.

Figure 2. Kaplan-Meier curve: stratified by age groups

Kaplan–Meier plots of survival for the entire cohort of patients with PMASC stratified by pediatric and adult age groups. Median survival for the adult and pediatric age groups was 9 and 16 months. Adult patients (n=93) observed markedly prolonged survival compared to the pediatric group (n=42) (p=0.030 on Log Rank analysis). For the adult group 6-months and 1-, 2-, 5-, 10-year survival rates were 74.2%, 61.1%, 38.9%, 21.9%, and 15.1%, respectively. The pediatric cohort demonstrated survival rates of 67.8%, 30.1%, 17.0%, 11.3%, and 11.3%.

Figure 3. Kaplan-Meier curve: stratified by sex

Kaplan–Meier plots of survival for the entire cohort of patients with PMASC stratified by sex. Median survival for males and females was 15 and 10 months. Males (n=78) observed prolonged survival compared to females (n=57) (p=0.042 on Log Rank analysis). For male patients 6-months and 1-, 2-, 5-, 10-year survival rates were 80.6%, 60.8%, 37.5%, 24.0%, and 16.5%, respectively. The female cohort demonstrated survival rates of 61.0%, 39.5%, 25.1%, 11.7%, and 9.7%.

Figure 4. Kaplan-Meier curve: stratified by tumor histology

Kaplan–Meier plots of survival for the entire cohort of patients with PMASC stratified by tumor histology. Median survival for AA and GB cases was 17 and 10 months. AA cases (n=76) observed prolonged survival compared to GB cases (n=59) (p=0.002 on Log Rank analysis). For patients with AA 6-months and 1-, 2-, 5-, 10-year survival rates were 82.7%, 60.0%, 42.4%, 24.3%, and 19.0%, respectively. The GB cohort demonstrated survival rates of 59.0%, 41.1%, 18.7%, 11.2%, and 7.0%.

Figure 5. Kaplan-Meier curve: stratified by EOR

Kaplan–Meier plots of survival stratified by EOR for the PMASC cohort with known surgical data (n=109). Median survival for the NS, Bx, PR and GTR groups were 9, 10, 11, and 24 months, respectively. For patients not undergoing surgery the 6-months and 1-, 2-year survival rates were 60.0%, 37.5% and 10.0%, respectively. Patients undergoing a biopsy procedure demonstrated 6-months and 1-, 2-, 5-, 10-year survival rates of 67.2%, 48.0%, 24.0%, 19.2%, and 9.6%. The PR group had survival rates of 71.4%, 45.2%, 35.2%, 13.7% and 10.3%. Finally, patients undergoing a GTR showed survival rates of 85.0%, 72.9%, 48.6%, 25.9% and 22.2%. When compared to the NS group by log-rank analysis only the GTR group seemed to be statistically different (p=0.002).

Figure 6

(A) Kaplan-Meier curve: stratified by the use of radiotherapy. Kaplan–Meier (KM) plots of survival for the entire cohort of patients with PMASC stratified by the use of radiotherapy. Median survival for the radiation and no-radiation groups was 15 and 5 months. Patients undergoing radiotherapy (n=109) showed a trend of prolonged survival compared to the no-radiation group (n=24) (p=0.068 on Log Rank analysis). (B) Kaplan-Meier curve: adult cohort stratified by the use of radiotherapy. KM plots for the adult cohort of patients with PMASC stratified by the use of radiotherapy. Median survival for radiation and no-radiation groups was 20 and 3 months. Patients undergoing radiotherapy (n=74) showed a trend of prolonged survival compared to the no-radiation group (n=17) (p=0.078 on Log Rank analysis). (C) Kaplan-Meier curve: pediatric cohort stratified by the use of radiotherapy. KM plots for the pediatric cohort of patients with PMASC stratified by the use of radiotherapy. Median survival for radiation and no-radiation groups was 9 and 13 months. Patients undergoing radiotherapy (n=35) did show a survival benefit compared to the no-radiation group (n=7) (p=0.924 on Log Rank analysis).

Figure 6

(A) Kaplan-Meier curve: stratified by the use of radiotherapy. Kaplan–Meier (KM) plots of survival for the entire cohort of patients with PMASC stratified by the use of radiotherapy. Median survival for the radiation and no-radiation groups was 15 and 5 months. Patients undergoing radiotherapy (n=109) showed a trend of prolonged survival compared to the no-radiation group (n=24) (p=0.068 on Log Rank analysis). (B) Kaplan-Meier curve: adult cohort stratified by the use of radiotherapy. KM plots for the adult cohort of patients with PMASC stratified by the use of radiotherapy. Median survival for radiation and no-radiation groups was 20 and 3 months. Patients undergoing radiotherapy (n=74) showed a trend of prolonged survival compared to the no-radiation group (n=17) (p=0.078 on Log Rank analysis). (C) Kaplan-Meier curve: pediatric cohort stratified by the use of radiotherapy. KM plots for the pediatric cohort of patients with PMASC stratified by the use of radiotherapy. Median survival for radiation and no-radiation groups was 9 and 13 months. Patients undergoing radiotherapy (n=35) did show a survival benefit compared to the no-radiation group (n=7) (p=0.924 on Log Rank analysis).

Figure 6

(A) Kaplan-Meier curve: stratified by the use of radiotherapy. Kaplan–Meier (KM) plots of survival for the entire cohort of patients with PMASC stratified by the use of radiotherapy. Median survival for the radiation and no-radiation groups was 15 and 5 months. Patients undergoing radiotherapy (n=109) showed a trend of prolonged survival compared to the no-radiation group (n=24) (p=0.068 on Log Rank analysis). (B) Kaplan-Meier curve: adult cohort stratified by the use of radiotherapy. KM plots for the adult cohort of patients with PMASC stratified by the use of radiotherapy. Median survival for radiation and no-radiation groups was 20 and 3 months. Patients undergoing radiotherapy (n=74) showed a trend of prolonged survival compared to the no-radiation group (n=17) (p=0.078 on Log Rank analysis). (C) Kaplan-Meier curve: pediatric cohort stratified by the use of radiotherapy. KM plots for the pediatric cohort of patients with PMASC stratified by the use of radiotherapy. Median survival for radiation and no-radiation groups was 9 and 13 months. Patients undergoing radiotherapy (n=35) did show a survival benefit compared to the no-radiation group (n=7) (p=0.924 on Log Rank analysis).