eMedicine Specialties > Oncology > Carcinomas of Endocrine Organs
Parathyroid Carcinoma: Treatment & Medication
Updated: May 4, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
- Multimedia
Treatment
Medical Care
No effective medical therapy for parathyroid carcinoma is known.6 Trials of chemotherapeutic agents have been generally disappointing with only anecdotal reports of success. This tumor is sufficiently rare that controlled trials are impossible.
Medical therapy is primarily geared toward management of the hypercalcemia that is often quite severe. Treatment is similar to hypercalcemia due to other causes. At initial presentation and for rapid treatment of severe hypercalcemia volume loading and diuresis with a calcium-wasting loop diuretic is the treatment of choice. The next line of therapy, used for chronic treatment, is the bisphosphonates. Detailed dosing information can be found below.
Hypercalcemia due to parathyroid cancer is often resistant to long-term medical management and is usually the cause of death in patients with metastatic disease.
Surgical Care
At present, resection of the parathyroid cancer is the only effective treatment.
- Preoperative care
- Because the hypercalcemia caused by parathyroid cancer is often severe, preoperative medical intervention to control hypercalcemia is often required.
- Volume expansion with isotonic saline and diuresis with furosemide is often adequate.
- Take care to ensure that any volume contraction is corrected before the operation.
- Operative management
- The goal of the initial operation is to remove the tumor en bloc with any adherent tissue, the ipsilateral thyroid lobe, and any enlarged lymph nodes.
- Because the diagnosis of malignancy is usually uncertain before the operation, the initial approach is the same as for benign primary hyperparathyroidism.
- Make a standard collar incision. While approaching the parathyroid, be alert for evidence of invasion into surrounding tissue or gland firmness that might indicate malignancy.
- If any indication of malignancy is noted, perform an en bloc excision.
- If any regional lymph nodes are enlarged, remove them.
- Recommendations on the precise extent of the dissection cannot be made because of the rarity of this condition, but an en bloc excision with negative margins and removal of the involved lymph nodes is probably adequate.
- Postoperative care
- Postoperative care is generally the same as for benign hyperparathyroidism.
- Bone hunger may be quite profound and require substantial doses of postoperative calcium.
- Resection of recurrence
- Reoperation for local and regional recurrence is indicated and may provide substantial palliation from hypercalcemia, in some cases for many years.
- Resection or ablation of pulmonary or hepatic metastases also may provide palliation.
- Long-term cure after a recurrence is virtually unknown.
Consultations
- Experienced surgeon - Surgical removal is the only effective treatment.
- Medical endocrinologist - Medical care of the hypercalcemia can be difficult and complex.
- Interventional radiologist - Percutaneous ablation or embolization of metastatic lesions may provide palliation.
- Radiation oncologist - External beam radiation therapy (EBRT) is controversial. It may decrease local recurrence when used in the adjuvant setting postoperatively but the evidence for this is not strong.7 It may also be used in specific circumstances for treatment of a metastasis. In general, however, parathyroid carcinoma is relatively resistant to radiation therapy.
Medication
No medical treatment is available for parathyroid carcinoma except to reduce hypercalcemia. However, hypercalcemia associated with parathyroid carcinoma is often severe and refractory to medical treatment.
Calcimimetic Agent
These agents bind to and modulate the parathyroid calcium-sensing receptor, increase sensitivity to extracellular calcium, and reduce parathyroid hormone secretion.
Cinacalcet (Sensipar)
Directly lowers parathyroid hormone (PTH) levels by increasing sensitivity of calcium-sensing receptor on chief cell of parathyroid gland to extracellular calcium. Also results in concomitant serum calcium decrease.
Adult
30 mg PO qd initially; titrate q2-4wk as needed to normalize calcium levels by sequential doses of 30 mg bid, 60 mg bid, 90 mg bid, and 90 mg tid/qid
Take with meals or immediately following; do not crush, chew, or cut tablets
Pediatric
Not established
Strong CYP450 2D6 inhibitor; may increase serum levels of CYP 2D6 substrates (eg, flecainide, vinblastine, thioridazine, tricyclic antidepressants); coadministration with CYP450 3A4 inhibitors (eg, ketoconazole, erythromycin, itraconazole) may decrease clearance
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Serum calcium reduction may cause lowered seizure threshold, paresthesia, myalgia, cramping, and tetany; monitor calcium and phosphorus levels closely within 1 wk following initial dose or dose changes, and then monthly (secondary hyperparathyroidism) and q2mo (parathyroid carcinoma); do not initiate treatment if serum calcium level below 8.4 mg/dL; adynamic bone disease may occur if iPTH levels suppressed below 100 pg/mL; caution with hepatic impairment; common adverse effects include nausea and vomiting
Bisphosphonate
Bisphosphonates are analogs of pyrophosphate and act by binding to hydroxyapatite in bone-matrix, thereby inhibiting the dissolution of crystals. They prevent osteoclast attachment to the bone matrix and osteoclast recruitment and viability.
Pamidronate (Aredia)
Inhibits normal and abnormal bone resorption. Appears to inhibit bone resorption without inhibiting bone formation and mineralization.
Adult
Moderate hypercalcemia: 60-90 mg IV as a single dose infused over 2-24 h
Severe hypercalcemia: 90 mg IV as a single dose infused over 2-24 h
Pediatric
Not established
None reported
Documented hypersensitivity; hypocalcemia
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Monitor hypercalcemia-related parameters, such as serum levels of calcium, phosphate, magnesium, and potassium, once treatment begins; adequate intake of calcium and vitamin D is necessary to prevent severe hypocalcemia; caution when administering bisphosphonates in patients with active upper GI problems; do not coadminister with alendronate for osteoporosis in postmenopausal women; renal toxicity decreases with IV infusions >2 h
Alendronate (Fosamax)
Available in the United States, but not yet indicated for treatment of hypercalcemia; alendronate probably is useful for long-term prevention of recurrence of hypercalcemia following use of more conventional therapy (ie, hydration and pamidronate). Useful in preventing and treating osteoporosis, which is a complication of prolonged mild hypercalcemia.
Adult
Not established; usual starting dose is 40 mg PO qam
Pediatric
Not established
None reported
Documented hypersensitivity; hypocalcemia, abnormalities of the esophagus, inability to stand upright for 30 min
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Must be taken at least 30 min before first food, beverage, or medication of the day and should be taken with large amounts of water; caution in renal impairment
Etidronate disodium (Didronel)
First-generation bisphosphonate that has been shown to increase bone density at spine and femoral neck, though studies have failed to demonstrate a decrease in fractures. Acts principally by inhibiting bone resorption and does not alter renal tubular reabsorption of calcium. The effects of etidronate increase as the dose increases.
Does not affect hypercalcemia in patients with hyperparathyroidism.
Adult
7.5 mg/kg/d IV diluted in approximately 250 mL of sterile NS over period of approximately 2 h for 3 d; hypocalcemia may occur when administered >3 d
Pediatric
Not established
Coadministration with calcium containing products and other multivalent cations decrease absorption
Documented hypersensitivity; hypocalcemia, renal impairment
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Monitor hypercalcemia-related parameters (eg, serum levels of calcium, phosphate, magnesium and potassium); maintain adequate intake of calcium and vitamin D to prevent severe hypocalcemia; caution if active upper GI problems; do not administer with alendronate for osteoporosis in postmenopausal women
Zoledronic acid (Zometa)
Inhibits bone resorption possibly by acting on osteoclasts or osteoclast precursors. Median duration of complete response (maintaining normalized calcium levels) and time to relapse reported as 32 and 30 d, respectively.
Adult
4 mg IV over at least 15 min qmo; hydrate patient prior to infusion; may repeat treatment if serum calcium does not return to desired level after 7 d
CrCl >60 mL/min: 4 mg
CrCl 50-60 mL/min: 3.5 mg
CrCl 40-49 mL/min: 3.3 mg
CrCl 30-39 mL/min: 3 mg
Pediatric
Not established
Concurrent administration with loop diuretics may increase risk of hypocalcemia
Documented hypersensitivity
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Caution in renal insufficiency (hold dose with increased CrCl); risk of renal deterioration increased with <15 min IV infusion; flu-like syndrome (fever, arthralgias, myalgias, skeletal pain), gastrointestinal reactions, anemia, insomnia, dyspnea, electrolyte and mineral disturbances (eg, low serum phosphate, calcium, magnesium, and potassium) may occur
Human calcitonin analogs
These agents promote the renal excretion of calcium, making them suitable for the treatment of hypercalcemia.
Calcitonin (Miacalcin, Osteocalcin)
Lowers elevated serum calcium in patients with multiple myeloma, carcinoma, or primary hyperparathyroidism. Can expect a higher response when serum calcium levels are high.
Onset of action is approximately 2 h following injection and activity lasts for 6-8 h. May lower calcium levels for 5-8 d by about 9% if given q12h. IM route is preferred at multiple injection sites with dose >2 mL.
Adult
4 IU/kg IM/SC q12h
Increase dose to 8 U/kg q12h if response is not satisfactory after 1-2 d and 8 IU/kg q6h if response remains unsatisfactory >2 d
Pediatric
Not established
None reported
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Hypocalcemia may occur; examine urine sediment during prolonged therapy
More on Parathyroid Carcinoma |
| Overview: Parathyroid Carcinoma |
| Differential Diagnoses & Workup: Parathyroid Carcinoma |
 Treatment & Medication: Parathyroid Carcinoma |
| Follow-up: Parathyroid Carcinoma |
| Multimedia: Parathyroid Carcinoma |
| References |
| « Previous Page | Next Page » |
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Further Reading
Keywords
parathyroid cancer, parathyroid gland, parathyroid carcinoma, parathyroid malignancy, parathyroid gland malignancy, hyperparathyroidism, bone disease, high serum calcium level, renal stones, hypercalcemia
