183 An Effect of Letrozole on Gastric Cancer? Fig. 7. Gastric biopsy (Formalin fixed paraffin embedded tissue stained with haematoxylin-eosin) showing gastric ulceration with invasive adeno- carcinoma of the stomach. After the patient recovered from the gastrectomy, surgical treat- ment of her breast cancer was discussed again with the patient, however she refused and opted to continue with letrozole treat- ment. She has been seen regularly in the outpatient clinic following the operation and in her last clinic visit, which was approximately 14 months postoperatively, she has gained 16 kg in weight and the palpable tumour in her left breast has significantly reduced in size. She also expressed her satisfaction with her treatment up to date and is still not keen on surgical treatment, therefore the letrozole has been continued at 2.5 mg daily dose with a view of reviewing the patient in another 6 months. She had a CT scan of her abdo- men which showed no evidence of recurrence of the gastric cancer. Discussion The original gastric biopsies of the patient showing invasive adenocarcinoma of the stomach, which was confirmed by two independent histopathologists being ER receptor negative is more likely to be a primary gastric tumour. Unfortunately Immuno- histochemical analysis could not be carried out as the samples were cut out of the block. Irrespective of whether the gastric cancer was primary or meta- static from breast cancer, in our patient following the resection of the stomach, there was no evidence of malignancy in the stomach and none in the 22 resected lymph nodes. After careful analysis and review of the patient we have concluded that this could be due to three possibilities: 1) The only treatment instigated between di- agnosis and resection of the gastric tumour was letrozole so, did le- trozole have an effect on the gastric cancer. As we mentioned pre- viously the main mechanism of action of letrozole is an aromatase inhibitor. We suggest that their might be other intracellular signal- ing pathways supported by evidence suggesting down regulation of genes associated with cell cycle and proliferation following letrozole treatment these changes could alter not only cellular expression but secondary consequences of cell death and clonal selection, in addition to longer term changes shown to alter vascularization, remodeling and the inflammatory response at the mitochondrial and extracellular matrix level.(14) This will need further research and studies to determine if letrozole could have a therapeutic ef- fect on gastrointestinal tumours. 2) Did the gastric cancer undergo spontaneous remission? This is unlikely however there are a few published cases in literature and the mechanism is not clearly un- derstood.(15) 3) Sampling error: Evidence of artefact or sampling error were investigated and double checked by two independent pathologists and discussed in the report and none were identified. We would also like to highlight the importance of conducting Immunohistochemical analysis when patients are diagnosed with stomach cancer and are also found to have Breast cancer. Unfortu- nately in our case Immuno-histochemical analysis was not carried out as the samples were cut out of the block. As we have discussed earlier Immunohistochemical analysis is very useful in differentiat- ing between primary stomach cancers from metastatic breast carci- noma of the stomach and hence the management of these patients. Conclusion In conclusion, a patient with oestrogen receptor positive breast cancer and oestrogen receptor negative gastric cancer was treated with letrozole and gastric resection. Independent histology by two pathologists pre-operatively diagnosed gastric adenocarcinoma.