Surgical management of incidentally discovered low-grade gliomas

Abstract

OBJECTIVEAlthough most patients with low-grade glioma (LGG) present after a seizure, a small proportion is diagnosed after neuroimaging is performed for a sign or symptom unrelated to the tumor. While these tumors invariably grow, some surgeons argue for a watchful waiting approach. Here, the authors report on their experience in the surgical treatment of patients with incidental LGG (iLGG) and describe the neurological outcomes, survival, and complications.METHODSRelevant cases were identified from a prospective registry of patients undergoing glioma resection at the University of California, San Francisco, between 1997 and 2019. Cases were considered iLGG when the lesion was noted on imaging performed for a reason unrelated to the tumor. Demographic, clinical, pathological, and imaging data were extracted from the electronic medical record. Tumor volumes, growth, and extent of resection were calculated from pre- and postoperative volumetric FLAIR sequences.RESULTSOne hundred thirteen of 657 (17.2%) first-time resections for LGG were for incidental lesions. The most common reasons for the discovery of an iLGG were headaches (without mass effect, 34.5%) or trauma (16.8%). Incidental tumors were no different from symptomatic lesions in terms of laterality or location, but they were significantly smaller (22.5 vs 57.5 cm3, p < 0.0001). There was no difference in diagnosis between patients with iLGG and those with symptomatic LGG (sLGG), incorporating both molecular and pathological data. The median preoperative observation time for iLGG was 3.1 months (range 1 month–12 years), and there was a median growth rate of 3.9 cm3/year. Complete resection of the FLAIR abnormality was achieved in 57% of patients with incidental lesions but only 23.8% of symptomatic lesions (p < 0.001), and the residual volumes were smaller for iLGGs (2.9 vs 13.5 cm3, p < 0.0001). Overall survival was significantly longer for patients with incidental tumors (median survival not reached for patients with iLGG vs 14.6 years for those with sLGG, p < 0.0001). There was a 4.4% rate of neurological deficits at 6 months.CONCLUSIONSThe authors present the largest cohort of iLGGs. Patient age, tumor location, and molecular genetics were not different between iLGGs and sLGGs. Incidental tumors were smaller, a greater extent of resection could be achieved, and overall survival was improved compared to those for patients with sLGG. Operative morbidity and rates of neurological deficit were acceptably low; thus, the authors advocate upfront surgical intervention aimed at maximal safe resection for these incidentally discovered lesions.

Pseudo-insular glioma syndrome: illustrative cases

“…Patients with a lesion consistent with incidental LGG should receive surgical resection, given the significant survival benefit associated with early surgery. 42 , 43 …”

Pediatric and Adult Low-Grade Gliomas: Where Do the Differences Lie?

“…In a large case series by Gogos et al GTR was achieved in 57% of incidental and 24% of symptomatic aLGGs, with a significantly shorter survival of symptomatic aLGGs (median 14.6 years) [54]. For adults, early resection resulted in a longer OS than observation and a delayed resection of aLGG [54]. To achieve a complete resection with the total removal of FLAIR abnormalities in aLGG is difficult, as the tumor is non-enhancing and often presents as normal tissue during surgery [7].…”

“…In adults, GTR is more likely to be achieved in incidental lesions than in symptomatic lesions, which is most probably due to their non-eloquent location. In a large case series by Gogos et al GTR was achieved in 57% of incidental and 24% of symptomatic aLGGs, with a significantly shorter survival of symptomatic aLGGs (median 14.6 years) [54]. For adults, early resection resulted in a longer OS than observation and a delayed resection of aLGG [54].…”

“…Adjuvant therapy is not considered for low-risk aLGG, with low-risk defined as age <40 years and a total resection of the FLAIR abnormalities in the postoperative MRI. For radiological tumor progression (>25% radiological increase of tumor size) or recurrence not amenable to surgery, adjuvant therapy is usually suggested [54,[67][68][69]. However, in adults, the recommended type of chemotherapy differs from pediatric patients, and for adults, concomitant radiotherapy (RT) is often suggested [7].…”

Modern surgical management of incidental gliomas

“…In a series of 143 gliomas, Pallud et al noted an inverse correlation between radiographic growth rates and survival, advocating for this parameter’s incorporation into treatment planning [ 35 ]. Additionally, iLGGs demonstrate a median Ki67 proliferative index of 5.0% [ 7 , 15 ], which is comparable to that of symptomatic LGGs, indicating that early surgical resection may be beneficial to improve prognosis and survival outcomes [ 7 , 15 , 36 ]. Gogos et al reported a key finding that 13% of iLGGs were observed to have IDH1/IDH2 wild-type genetic features which are associated with a worse prognosis, however, this information would not have been revealed if treatment had been delayed [ 36 ].…”