Lynch syndrome is an autosomal dominant disorder leading to cancer predisposition caused by mutations in mismatch repair genes. There is minimal published experience treating glioblastoma in patients with Lynch syndrome. We report a patient with Lynch syndrome who was initially diagnosed with a left occipital isocitrate dehydrogenase (IDH) wild-type glioblastoma. After resection, she was treated with chemoradiation, followed by tumour treating fields. Three years after diagnosis, recurrence was resected. After refusing cytotoxic chemotherapy, decision was made to treat with off-label nivolumab concurrently with radiation. She has been maintained on nivolumab without recurrence of her glioblastoma now over 5 years out from her initial diagnosis. This case provides the first report of glioblastoma in a patient with Lynch syndrome responding to nivolumab and concurrent radiation. In patients with Lynch syndrome and glioblastoma, immunotherapy in the form of nivolumab may be an alternative option to standard cytotoxic chemotherapy.
Tumor mutation burden determined by a 645-cancer gene panel and compared with microsatellite instability and mismatch repair genes in colorectal cancer
