184 Ahmed EL Hadi, et al. Post-operatively, independent analysis of the resected stomach, omentum, pancreas and lymph nodes revealed no evidence of gas- tric cancer. This suggests the possibility of letrozole having an ef- fect on gastric cancer. Further studies are needed. Acknowledgments We would like to thank the Pathology Department at the Aneu- rin Bevan Healthcare NHS trust, specially Dr. Elsie Wessels (Con- sultant Pathologist) for her help and valuable contribution with this case. We are also very grateful for Professor G Williams (Consultant Pathologist at the University Hospital of Wales) for his valuable opinion in regards to the diagnosis of this case. References 1. Yager JD, Davidson NE. Estrogen carcinogenesis in breast can- cer. N Engl J Med 2006;354:270-282. 2. Bhatnagar AS. The discovery and mechanism of action of le- trozole. Breast Cancer Res Treat 2007;105(Suppl 1):7-17. 3. Goss PE, Ingle JN, Martino S, Robert NJ, Muss HB, Piccart MJ, et al. A randomized trial of letrozole in postmenopausal women after five years of tamoxifen therapy for early-stage breast cancer. N Engl J Med 2003;349:1793-1802. 4. Goss PE, Ingle JN, Martino S, Robert NJ, Muss HB, Piccart MJ, et al. Randomized trial of letrozole following tamoxifen as extended adjuvant therapy in receptor-positive breast cancer: updated findings from NCIC CTG MA.17. J Natl Cancer Inst 2005;97:1262-1271. 5. Tremblay F, Jamison B, Meterissian S. Breast cancer mas- querading as a primary gastric carcinoma. J Gastrointest Surg 2002;6:614-616. 6. Yim H, Jin YM, Shim C, Park HB. Gastric metastasis of mam- mary signet ring cell carcinoma--a differential diagnosis with primary gastric signet ring cell carcinoma. J Korean Med Sci 1997;12:256-261. 7. Matsui M, Kojima O, Kawakami S, Uehara Y, Takahashi T. The prognosis of patients with gastric cancer possessing sex hor- mone receptors. Surg Today 1992;22:421-425. 8. van Velthuysen ML, Taal BG, van der Hoeven JJ, Peterse JL. Expression of oestrogen receptor and loss of E-cadherin are diagnostic for gastric metastasis of breast carcinoma. Histopa- thology 2005;46:153-157. 9. Wick MR, Lillemoe TJ, Copland GT, Swanson PE, Manivel JC, Kiang DT. Gross cystic disease fluid protein-15 as a marker for breast cancer: immunohistochemical analysis of 690 human neoplasms and comparison with alpha-lactalbumin. Hum Pathol 1989;20:281-287. 10. Mazoujian G, Pinkus GS, Davis S, Haagensen DE Jr. Im- munohistochemistry of a gross cystic disease fluid protein (GCDFP-15) of the breast. A marker of apocrine epithelium and breast carcinomas with apocrine features. Am J Pathol 1983;110:105-112. 11. Bhargava R, Beriwal S, Dabbs DJ. Mammaglobin vs GCD- FP-15: an immunohistologic validation survey for sensitivity and specificity. Am J Clin Pathol 2007;127:103-113. 12. O'Connell FP, Wang HH, Odze RD. Utility of immunohisto- chemistry in distinguishing primary adenocarcinomas from metastatic breast carcinomas in the gastrointestinal tract. Arch Pathol Lab Med 2005;129:338-347. 13. Jones GE, Strauss DC, Forshaw MJ, Deere H, Mahedeva U, Mason RC. Breast cancer metastasis to the stomach may mimic primary gastric cancer: report of two cases and review of literature. World J Surg Oncol 2007;5:75. 14. Miller WR, Larionov A. Molecular effects of oestrogen depri- vation in breast cancer. Mol Cell Endocrinol 2011;340:127-136. 15. Challis GB, Stam HJ. The spontaneous regression of cancer. A review of cases from 1900 to 1987. Acta Oncol 1990;29:545- 550.