INDEPENDENT PERITONEAL CANCER, NEARLY MISSED AS A METASTASIS FROM LUNG CANCER

Abstract

SESSION TITLE: Medical Student/Resident Lung Cancer Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Lung carcinoma is the leading cause of cancer-related mortality and nearly 50% of cases exhibit distal metastasis at the time of diagnosis. The most common sites of metastasis are brain, spine, nerve, adrenal gland, bone, liver, pleura, but rarely involves the peritoneum.[1] Peritoneal involvement in lung cancer is assumed to be due to metastasis from primary lung cancer. The occurrence of primary peritoneal adenocarcinoma and lung cancer together in one person is uncommon and difficult to distinguish from the metastatic spread. [2] CASE PRESENTATION: A 73-year-old female, smoker of 30 pack-year, presented with symptoms of abdominal bloating, distension, and loss of appetite. Computed tomography(CT) chest, abdomen, and pelvis showed moderate abdominal ascites consistent with peritoneal carcinomatosis, along with a 4.3 cm mass in the left lower lobe of the lung and 1.1 cm left-sided mediastinal lymph node. Paracentesis with ascitic fluid analysis was positive for adenocarcinoma. [Picture 1] She underwent endobronchial ultrasound with biopsy with immunohistochemistry staining which showed poorly differentiated squamous cell carcinoma [Picture 2]. Metastatic workup with a magnetic resonance imaging(MRI) of the brain was negative. Positron emission tomography-computed tomography scan showed a Fluorodeoxyglucose avid left lower lobe lung lesion with hilar and subcarinal adenopathy, consistent with primary lung malignancy. Pelvic ultrasound showed enlarged uterus secondary to multiple intramural fibroids. Labs showed Carcinoembryonic antigen level 1.2 and Alpha-fetoprotein 1.6. Oncology planned to start on carboplatin and paclitaxel along with pembrolizumab every 3 weeks for 4 cycles, followed by maintenance therapy with pembrolizumab every 3 weeks. She reported improvement in the abdominal bloating with the removal of 2-3 liter of peritoneal fluid weekly and symptomatic treatment. The patient continued to feel excessively tired and deteriorated within a few weeks. Unfortunately, the patient passed away before the start of the treatment. DISCUSSION: Peritoneal metastasis of primary lung carcinoma is very rare, only present in 2.7–16% of all lung cancer patients.[3] Advanced stage IV non-small cell lung cancer (NSCLC) and peritoneal adenocarcinoma can present in the same patient together, like in our case, which can be easily missed assuming it as metastatic cancer. Management of two separate cancers requires individualized treatment plans dissimilar to standard practices in the setting of a single tumor. A 1-year survival rate after cytotoxic chemotherapy is only 29% in patients with advanced NSCLC hence priority must be given to the treatment regimen that improves symptoms and prolongs survival. CONCLUSIONS: Therefore, one should always be suspicious and more effort should be made to improve the diagnostic approach and management to rule out any other underlying malignancy. Reference #1: McNeill PM, Wagman LD, Neifeld JP. Small bowel metastases from primary carcinoma of the lung. Cancer. 1987;59:1486–1489. Reference #2: MARÍA SERENO,1. Lung cancer and peritoneal carcinomatosis. Oncol Lett. 2013 Sep; 6(3): 705–708 Reference #3: Abrams HL, Spiro R, Goldstein N. Metastases in carcinoma; analysis of 1000 autopsied cases. Cancer. 1950;3:74–85. DISCLOSURES: No relevant relationships by Mary Grace Bethala, source=Web Response No relevant relationships by Apurwa Karki, source=Web Response No relevant relationships by Salman Khan, source=Web Response No relevant relationships by Shobha Mandal, source=Web Response