Sigmoid colon cancer associated with primary hyperparathyroidism: report of a case.

We present herein a case of sigmoid colon cancer associated with primary hyperparathyroidism (PHP). PHP is known to be associated with malignancy, and decreased intracolonic calcium (Ca) resulting from increased vitamin D (VD) levels may play a role in colorectal carcinogenesis. PHP was diagnosed in this patient by preoperative screening blood chemistry examination. The blood level of intact parathyroid hormone (PTH) was elevated and a parathyroid gland scintigram demonstrated abnormal uptake near the right lower lobe of the thyroid. There was no evidence of bone metastasis, and a sigmoid colectomy was performed with curative intent. The patient had an uneventful postoperative course without a critical elevation of the serum Ca level. This case report suggests that a relationship exists between PHP and colon cancer, and the possible mechanisms of this association are presented in our discussion.