Early Resection versus Watchful Waiting in Low-Grade Gliomas

The World Health Organization has identified grade II astrocytomas, oligodendrogliomas, and oligoastrocytomas as diffuse low-grade gliomas (LGGs). Surgery is not usually considered for treatment of LGGs and, because current evidence of the efficacy of surgery relies on uncontrolled surgical series alone, the effect of surgery on survival is not clear.

According to researchers, treatment strategies vary considerably between neurosurgical centers. Uncontrolled surgical series can be greatly affected by selection bias because patients with favorable outcomes may have fared better regardless of treatment, according to researchers. Watchful waiting until progression has been reported as safe; however, improved survival and delayed time to malignant transformation if total resection of the tumor is achieved has also been reported.

The researchers recently conducted a retrospective population-based parallel cohort study to determine if early tumor resection, as the preferred strategy, improves survival in patients with LGG compared with a strategy favoring biopsy and watchful waiting. They reported study results in the Journal of the American Medical Association [2012;308(18):1881-1888].

The study was conducted at 2 Norwegian university hospitals using different surgical treatment strategies. Both neurosurgical departments are exclusive providers in adjacent geographical regions with regional referral practices.

Hospital A utilized a wait and scan approach and only offered a resection of suspected LGGs if a safe total resection seemed possible based on preoperative planning or for relieving symptoms of mass effect. Hospital B introduced the concept of 3-dimensional (3-D) ultrasound brain surgery and, since 1998, has used the SonoWand^® neuronavigation system with 3-D ultrasound-based intraoperative imaging in its tumor operations. Hospital B favored early resection for patients with LGGs.

The primary outcome measure of the study was overall survival based on regional comparisons without adjusting for administered treatment.

To ensure uniform classification and inclusion, histopathology specimens from all adult patients diagnosed with LGG from 1998 through 2009 were subjected to a blinded histopathologic review; follow-up was completed by April 22, 2011.

A total of 153 patients with diffuse LGGs were included; 66 were from hospital A and 87 from hospital B.

At the end of follow-up, 52% (n=34) of patients from hospital A had died compared with 32% (n=28) of those from hospital B. Overall, survival was significantly longer if treated at the center favoring early resection (hospital B) than at the center favoring biopsy and watchful waiting (hospital A; P=.01).

Over time, the survival advantage increased: 1-year survival was 89% versus 89%, however, expected 3-year survival was 70% for patients treated at hospital B versus 80% at hospital A, expected 5-year survival was 60% versus 74%, and expected 7-year survival was 44% versus 68%.

At hospital A (watchful waiting), median survival was 5.98 years. Median survival has not yet been reached at hospital B (early resection).

There were no significant differences in surgical complications (9% in the watchful waiting group vs 8% in the early resection group; P=.82) or acquired deficits (18% in the watchful waiting group vs 21% in the early resection group; P=.70).

In conclusion, the researchers stated, “For patients in Norway with LGG, treatment at a center that favored early surgical resection was associated with better overall survival than treatment at a center that favored biopsy and watchful waiting. This survival benefit remained after adjusting for validated prognostic factors.”