Surgical resection of solitary omental metastasis from non-small cell lung cancer: Report of three cases

Omental Metastasis from ALK-positive Lung Cancer — A Case Report

Background

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related deaths worldwide. In Ireland alone, there are over 2500 new cases of lung cancer diagnosed each year. It ranks fourth among the most common cancers and causes 21% of all cancer-related deaths.

Lung cancers usually metastasize to the liver, brain, bone, and adrenal glands—rarely affecting the abdomen. To our knowledge, there are 8 previous studies in the literature to date which involve omental metastasis from NSCLC.

Case presentation

A 73-year-old lady presented with a history of productive cough for 18 months. A chest X-ray showed a suspicious 6 cm mass in the right lower zone. She went on to have an endobronchial biopsy which confirmed a moderately differentiated adenocarcinoma of the lung which was ALK positive. She went on to have staging PET and CT scans and was staged as cT3N2M0. She was not a suitable candidate for surgery so she had radical chemo-radiotherapy with 4 cycles of cisplatin pemetrexed followed by radical dose sequential radiotherapy. Post treatment CT showed the tumor to be more spiculated in appearance. She was ineligible for Durvalumab maintenance therapy due to the extensive pneumonitis following her radiotherapy which required a prolonged course of steroids. Interval scans every 3 months did not show any progression of disease.

She presented to the hospital 13 months post her diagnosis with progressive abdominal swelling. Restaging CT scans showed extensive omental infiltration, the presence of multiple peritoneal nodules, and progression of her pulmonary disease with new brain metastasis. Cytological analysis of the ascitic fluid confirmed metastasis followed by omental biopsy which confirmed metastatic ALK-positive NSCLC. She went on to have targeted treatment with alectinib. She tolerated the treatment well. Restaging scans done 3 months later showed good partial response to therapy.

Conclusion

In conclusion, ALK-positive NSCLC with metastasis to the omentum is very rare. However, in patients with atypical symptoms like ascites, the possibility of a metastasis must be considered and repeat biopsy is always recommended. A targeted therapy in the selected patients has shown a more durable response than chemotherapy.

Surgical approach in oligometastatic non-small cell lung cancer

The vast majority of lung cancer (80%) are non-small cell lung cancer (NSCLC) presenting in huge proportion of patients in a metastatic stage at the time of diagnosis with an overall survival (OS) of only 6 months. Standard treatment at this stage involves systemic platinum based chemotherapy improving the OS for only few months. For the vast majority of patients disease progression occurs and cure cannot achieved. An exception to this general rule is represented by patients with a limited number of metastasis (approximately 7% of patients with metastatic NSCLC): in 1995 Hellman and Weichselbaum introduced the term "oligometastatic" for a selected group of patients with metastatic disease. Several retrospective studies have been published and documented an improved outcome in patients managed surgically. The purpose of this narrative review is to gather all relevant information and present the various clinicopathological and generic aspects of diagnosis, management strategies and prognostic factors in patients with oligometastatic NSCLC. The key for long term survival includes radical treatment of the primary NSCLC, single organ site with either synchronous or metachronous presentation, a disease free interval to be as long as possible and the absence of intrathoracic lymph node spread (N0). A more accurate staging with combination of FDG-PET and CT scan can have on impact on the survival rates due to an increased accuracy in mediastinal staging and in the diagnosis of distant metastasis. No randomized data but only retrospective series are available to date to address this topic: in the future, additional prospective studies will be necessary to provide robust evidence to support the surgical resection as treatment of oligometastatic NSCLC.

Surgical management of oligometastatic non-small cell lung cancer

The oligometastatic stage IV non-small cell lung cancer (NSCLC) offers a new surgical opportunity. New reported data is showing that surgery can offer a reasonable benefit, in terms of long-term survival, to some patients. The advantages of surgical treatment rely on a more adequate patient selection and a better understanding of the biology of these tumors. Currently, mediastinal involvement of the primary tumor can be identified as the most important prognostic variable after curative-intent of synchronous or metachronous metastasis. It seems clear that the routine use of combined FDG-PET and CT will help to detect the more favorable cohort of oligometastatic patients. As expected, pathological T staging of the primary tumor and the completeness of its resection are also crucial factors influencing final results. The real benefit of the local treatment over synchronous or metachronous metastasis is controversial with series showing better outcomes for metachronous lesions than for synchronous and others offering equal results. Also non conclusive results appear when analyzing different sites of metastasis. Retrospective series tend to show different outcomes depending on the affected organ while usually no differences are found in prospective ones. Most of the current evidence is based on retrospective studies on patients collected along extended periods of time. That represents a great limitation to the knowledge on this topic. Some prospective analyses have added some insight, but still the quality of the evidence is too low to allow drawing robust conclusions. As frequently concluded, prospective well designed investigation is requested to ascertain the value of surgery in this specific population of patients with extended NSCLC.