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Jeffrey
E. Lee, M.D. |
Directed operations such as sentinel lymph node mapping can potentially improve the effectiveness of staging and therapy and at the same time minimize morbidity. Similarly, patients with primary hyperparathyroidism can undergo a directed operation with high success and low morbidity when a combination of preoperative sestamibi imaging and the rapid intraoperative assay for parathyroid hormone (rPTH) is used. This approach has become an important component of a minimally invasive parathyroidectomy that utilizes small incisions and local anesthesia and has been applied to the treatment of patients undergoing initial and reoperative parathyroid surgery.
Technetium (Tc)-99m sestamibi imaging has become a standard part of the preoperative evaluation of patients with hyperparathyroidism. In approximately 80% of patients, the technique successfully localizes a parathyroid adenoma, which allows for a directed operation. In the 20% of patients in whom localization is unsuccessful, a repeat study following short-term thyroid suppression with liothyronine is safe and can result in successful localization.
At M. D. Anderson Cancer Center, we employ an rPTH assay that delivers results within 15 minutes of specimen collection. Baseline samples are compared with samples taken five and 10 minutes postexcision. A 50% drop in the rPTH value from baseline is indicative of clinical cure in patients with primary hyperparathyroidism. A lesser drop in the rPTH level calls for bilateral neck exploration to determine the presence or absence of multigland disease. In patients with multiple endocrine neoplasia type 1, who typically have multigland disease and are at risk for recurrent hyperparathyroidism, it is reasonable to target an 80% fall in the rPTH value; this rate also works well for patients with secondary hyperparathyroidism or parathyroid hyperplasia. In these patients, it is also desirable to have the rPTH level fall to within the normal range.
While not essential to the routine management of patients with primary hyperparathyroidism, intraoperative gamma probe localization can be used. The gamma probe may be particularly helpful during reoperative surgical procedures.
We have found that preoperative sestamibi scintigraphy, combined with the rPTH assay, allows for a successful directed parathyroidectomy in most patients and that this minimally invasive approach is well tolerated. Patients appreciate this approach because, most of the time, it allows them to avoid the side effects of general anesthesia. Their recovery is faster and more comfortable, and surgery can usually be performed as an outpatient procedure. As an endocrine surgeon, I find it satisfying to be able to perform a directed operation and be confident before leaving the operating room that the patient’s hyperparathyroidism has been cured.
For more information on this topic or for questions about M. D. Anderson’s treatments, programs, or services, call askMDAnderson at (877) MDA-6789.
Other articles in OncoLog, September 2003 issue:
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