This article is more than 5 years old. Information may no longer be current.
Radiation therapy warranted for treatment of pituitary adenomas
Click Here to Manage Email Alerts
When surgical or medical treatments fail, radiation therapy may be the best alternative for managing pituitary adenomas in certain patients. In a recently published paper in the Journal of Clinical Endocrinology & Metabolism, reviewers discuss different options and potential adverse events associated with radiation therapy.
In their clinical review, Jay S. Loeffler, MD, and Helen A. Shih, MD, MPH, both of the department of radiation oncology at Massachusetts General Hospital and Harvard Medical School, outline indications for radiation therapy in patients with pituitary adenomas. According to Loeffler and Shih, appropriate candidates include patients who do not qualify for surgery; have tumor recurrence or progression after surgery; are hormonally uncontrolled despite surgery and medical therapy; have tumor extension that cannot be surgically addressed; or have surgically inaccessible adenomas.
The reviewers discuss two types of radiation schedules: stereotactic radiosurgery and fractionated radiation. They said stereotactic radiosurgery is preferred because it requires only one visit, whereas fractionated therapy is administered in small daily doses for 5 days per week during a period of 5 to 6 weeks. Risk for injury to normal tissue, however, is lower with fractionated therapy.
The reviewers also recommend doses of 18 Gy for nonfunctioning pituitary adenomas and 20 Gy for functioning pituitary adenomas during stereotactic radiosurgery. In the case of fractionated therapy, they recommend using 45 Gy to 50.4 Gy delivered at 1.8 Gy daily for nonfunctioning adenomas and 50.4 Gy to 54 Gy delivered at 1.8 Gy daily for functioning adenomas. Loeffler and Shih suggest stopping medical treatment at least 1 month before initiating radiation therapy.
The most common problem associated with radiation therapy for management of pituitary adenomas is hypopituitarism. According to several studies, nearly all patients developed the condition after treatment, Loeffler and Shih said in the review. Even so, rates of other adverse events remain low.
“Radiation can achieve local control rates of 90% to 100% across all pituitary adenoma types and biochemical complete response in approximately 50% of patients with even more achieving hormonal normalization with addition of medical therapy,” the reviewers wrote. “Clinical data to date provide useful results to guide refinement of radiation dose and dose schedules to optimize therapeutic efficacy while minimizing potential treatment-related complications.” – by Melissa Foster
For more information:
Disclosure: Drs. Loeffler and Shih report no relevant financial disclosures.
|
|
This article provides an excellent review of radiation for pituitary tumors. It starts with a review of different techniques; however, the authors continue to make this more complicated than it needs to be. For example, there are only two forms of irradiation using either particles (proton beam) or high-energy photons (all the other techniques). The authors are definitely in favor of delivering radiation in one dose (stereotactic radiosurgery) over fractionated therapy, stating that the stereotactic surgery is more convenient and there is a quicker response; there is no disagreement that it is more convenient (one sitting), but there is not convincing data that it is faster. The authors also suggest that all medical therapy be stopped for a month before radiation. This may be true for somatostatin analogues for growth hormone secreting tumors, but use of other agents such as Metopirone (Novartis) for adrenocorticotropic hormone-secreting tumors, which acts at the adrenal level, may not be required. Another somewhat misleading statement is that smaller tumors do better with irradiation, and that because of this, tumor debulking with surgery is suggested. This has not been substantiated in controlled studies. The authors also state that growth hormone is not evaluated in many series because replacement in adults is typically not indicated. Most endocrinologists replace GH in GH-deficient adults, which occurs after surgery, and/or in irradiated patients.
The article is well referenced and well written and is worth reading by endocrinologists taking care of patients with pituitary tumors. The authors nicely point out that radiation should be used in patients failing surgery and medical therapy and not routinely after pituitary surgery. This is especially true in this era with the development of new drugs that eliminate, in many cases, the need for irradiation.
– David M. Cook, MD
Professor of Medicine
Oregon Health & Science Center
Disclosure: Dr. Cook reports receiving grant money from Eli Lilly
and Endo Pharmaceuticals.
He is also a speaker for Pfizer, Genentech and Novo
Nordisk.
|
|
This manuscript is a terrific and well-balanced review of the use of radiation therapy in the management of pituitary adenomas. Radiation therapy is generally utilized as adjuvant therapy following incomplete surgery or in the setting of progressive tumor that is not surgically amenable or medically responsive. The authors do a nice job in summarizing the indications for radiation, efficacy of conventional fractionated and stereotactic radiation for specific tumors, and associated risks. This manuscript is highly balanced in its appraisal of both the benefits and limitations of radiation therapy. Clinicians need to clearly understand these indications and limitations when prescribing radiation therapy in such patients.
– Laurence Katznelson, MD
Professor of
Medicine and Neurosurgery
Medical Director, Pituitary Center
Stanford
University School of Medicine
Disclosure: Dr. Katznelson reports financial, business or organizational interests in Ipsen, Novartis and Novo Nordisk.
 |
Follow EndocrineToday.com on Twitter. |