It’s even worse than being told you have a brain tumor: having a tumor so large, it’s in a category all its own. Giant pituitary adenoma is a so-called “benign” tumor that can cause visual loss and impair many of the body’s most basic functions. But fortunately, even the largest of these giant tumors—which can grow to the size of an egg and invade nearby structures--can be treated effectively using a multimodality approach starting with minimally invasive surgery through the nose, according to a new study at the John Wayne Cancer Institute at Saint John’s Health Center.
Pituitary adenomas are noncancerous tumors of the pituitary, the master gland that rules the endocrine system. Located in the skull base below the brain and behind the nasal cavity, the pituitary secretes powerful hormones that coordinate other glands, controlling such basic functions as growth and development, metabolism, the stress response, sexual function and water balance. Pituitary adenomas arise in about 1 in 1,000 individuals; about 10% are giant adenomas, 4 cm in diameter or larger.
As adenomas enlarge, they can cause pituitary gland failure by cutting off the flow of hormones. Headaches, visual loss and other symptoms may develop slowly over months or years, but can also happen rapidly over just a few hours if there is bleeding into the tumor, called “pituitary apoplexy.” Giant adenomas often grow around the pituitary gland and skull base into areas where critical blood vessels and nerves travel, making complete surgical removal impossible.
Endonasal surgery allows doctors to remove many kinds of brain tumors through a nostril. Reaching the tumor through a natural opening eliminates the need for traditional open-skull surgery (craniotomy) and in experienced hands, creates less trauma, fewer complications and a shorter recovery time. “Patients prefer the idea of a minimally invasive procedure through a natural opening,” said Daniel F. Kelly, MD, Director of Saint John’s Brain Tumor Center, faculty member at the John Wayne Cancer Institute at Saint John’s, and senior author of the study.
The procedure is performed using an operating microscope and an endoscope (a surgical telescope) for highly magnified, high-definition panoramic views of the surgical site. Specialized instruments are passed through the nasal cavity into the skull base to remove the tumor. Like GPS for the brain, a computerized guidance system for surgical navigation completes the high-tech arsenal of modern endonasal skull base surgery.
The new study reviewed 10 years worth of cases involving 51 giant adenoma patients operated on by Dr. Kelly. Their symptoms included progressive visual loss, hormonal problems, tumor bleeding and/or headaches. Using a multimodality approach combining surgery with focused radiation therapy and/or medical therapy, tumors were effectively controlled in 96 percent of patients. Approximately 60 percent required only endonasal surgery, while about 40 percent received surgery plus one or more additional treatments to control residual tumor.