Understanding the clinical course of genotype-negative MEN1 patients can inform management strategies

It is unclear whether genotype-negative clinical multiple endocrine neoplasia type 1 patients derive equal benefit from prospective surveillance as genotype-positive patients.

In this retrospective cohort study, we compared genotype-negative patients with clinical multiple endocrine neoplasia type 1 with genotype-positive index cases. Primary outcome was age-related penetrance of manifestations; secondary outcomes were disease-specific survival and clinical course of endocrine tumors.

We included 39 genotype-negative patients with clinical multiple endocrine neoplasia type 1 (Male: 33%) and 63 genotype-positive multiple endocrine neoplasia type 1 index cases (Male: 59%). Genotype-negative patients with clinical multiple endocrine neoplasia type 1 were 65 years old at last follow-up; genotype-positive multiple endocrine neoplasia type 1 index cases were 50 (P < .001). Genotype-negative patients with clinical multiple endocrine neoplasia type 1 were significantly older at their first and second primary manifestation. Only 1 developed a third primary manifestation. No genotype-negative patients with clinical multiple endocrine neoplasia type 1 with primary hyperparathyroidism and a pituitary adenoma developed a duodenopancreatic neuroendocrine tumor. Disease-specific survival was significantly better in genotype-negative patients with clinical multiple endocrine neoplasia type 1. In genotype-negative patients with clinical multiple endocrine neoplasia type 1, primary hyperparathyroidism was single-gland disease in 47% of parathyroidectomies versus 0% in genotype-positive multiple endocrine neoplasia type 1 index cases. In genotype-negative patients with clinical multiple endocrine neoplasia type 1, 17% of duodenopancreatic neuroendocrine tumors were multifocal versus 68% in genotype-positive multiple endocrine neoplasia type 1 index cases. Genotype-negative patients with clinical multiple endocrine neoplasia type 1 had more pituitary macroadenomas, fewer prolactinomas, and more somatotroph adenomas.

Genotype-negative patients with clinical multiple endocrine neoplasia type 1 have a different clinical course than genotype-positive multiple endocrine neoplasia type 1 index cases. This may support a separate classification and a tailored surveillance regimen. Of the genotype-negative patients with clinical multiple endocrine neoplasia type 1 who had parathyroidectomy, almost half had no evidence of multigland disease and may be potential candidates for a more targeted single-gland approach.