Endocrine Abstracts

Introduction

Many transsexual patients are concerned about the risk of cancer associated with hormonal gender-affirming therapy. However, the general risk seems to be very low. We hereby report the case of a strikingly large gastrointestinal stromal tumor (GIST) in a male-to-female transsexual patient, after 25 years of hormonal therapy.

Methods

Review of the patient’s clinical records and the relevant literature.

Background

GISTs are mesenchymal tumors arising from the smooth muscle pacemaker interstitial cell of Cajal. Most are gastric, but GISTs occurring elsewhere in the gastrointestinal tract have a higher malignant potential. About 85% derive for mutations in the KIT gene (encoding a receptor tyrosine kinase protein). They may present as intramural smooth muscle cell tumors, similar to uterine leiomyomas. However, these last tumors express estrogen and progesterone receptors and are hormone-dependent. On the other hand, GISTs have nor been shown to express these receptors and are generally not considered as hormone-dependent. The mainstay of GIST therapy is surgery, but tirosin-kinase inhibitors such as imatinib are useful as adjuvants.

Case report

A 46 year-old female transsexual patient had been on estrogen plus antiandrogen since she was 20 years old; currently on 4.59 mg of estradiol (transdermal aerosol) and 75 mg of cyproterone acetate (oral) daily, maintaining suppressed LH and FSH, and testosterone and estradiol within the normal fertile female range. She had undergone bilateral augmentation mammoplasty but not genital reassignment surgery. Last year, she presented a large indolent abdominal mass, and the FDG PET-CT scan showed a giant GIST (size 196 mm transverse × 92 mm posteroanterior × 124 mm craniocaudal), centered in the greater omentum but contacting non-invasively also the stomach, the left liver lobe, the pancreas and the transverse colon. The affinity for FDG was low (SUVmax 3.04), similar to that of the hepatic parenchyma, suggesting a low grade of malignancy. There were no pathological FDG deposits outside the tumoral mass, with no suspicious adenopathies and no signs of liver, lung, adrenal or bone metastases. The patient underwent surgery and is currently being treated with imatinib. The tumor tested negative for estrogen and progesterone receptors, and following the patient’s wishes the hormonal therapy has not been withdrawn.

Conclusion

A GIST has never to our knowledge been reported in a transsexual patient. Although the unusual size of our patient’s tumor might raise concerns about the possible implication of the hormone therapy, there is no clear rationale for them.