Synchronous lung and gastric cancers successfully treated with carboplatin and pemetrexed: a case report

INTRODUCTION Lung and gastric cancers are the first and second leading causes of death from cancer worldwide, and are especially prevalent in Eastern Asia. Relatively few reports are available in relation to the treatment and outcome of synchronous lung and gastric cancers, although there are increasing numbers of patients with these cancers. Efforts to develop more effective drugs for the treatment of synchronous cancers, without serious adverse effects, have been intensifying. Pemetrexed, a multi-targeted antifolate enzyme inhibitor, was approved by the United States Food and Drug Administration as a first-line chemotherapy for advanced non-squamous non-small cell lung cancer in 2007. Although clinical activity against several tumor types of adenocarcinoma, including gastric cancer, has been demonstrated, the efficacy of pemetrexed for gastric cancer remains to be fully evaluated. CASE PRESENTATION We report a case involving a 62-year-old Japanese woman with synchronous locally-advanced poorly-differentiated lung adenocarcinoma and poorly-differentiated gastric adenocarcinoma, containing signet-ring cells distinguished by immunohistochemical profiles. She had been treated with carboplatin and pemetrexed as a first-line chemotherapy for lung cancer, and had achieved partial responses for both lung and gastric cancers. These responses led to a favorable 12-month progression-free survival after the initiation of chemotherapy, and the patient is still alive more than 33 months after diagnosis. CONCLUSIONS This case suggests a new chemotherapeutic regimen for patients with synchronous multiple primary cancers that have an adenocarcinoma background.