This study is conducted to test the hypothesis that patients with lung cancer undergoing treatment with immunotherapy, chemotherapy and tyrosine Kinase Inhibitors receiving a high protein diet and supplemented with fish oil will improve muscle mass, therapeutic response and modulate the intestinal microbiota within a 4 month period.

Lung cancer (PC) is the most prevalent tumor. The loss of muscle mass, myosteatosis and changes in body composition have been associated with inflammation in cancer and PUFA n-3 have been shown to be an important modulator of the inflammatory response and epigenetic mechanisms. Additionally, the intestinal microbiome has received prominence with the use of immunotherapy, as it is demonstrating that resistance to this therapy can be attributed to the abnormal composition of the intestinal microbiome. Aims: The purpose of this study is to assess the effects of fish oil supplementation in the modulation of lean mass and intestinal microbiome in patients with lung cancer undergoing treatment with immunotherapy, chemotherapy and Tyrosine Kinase Inhibitors receiving a high-protein diet. Methods: Fifty patients will be randomly allocated either to treatment with fish oil or to placebo for 4 months. The following assessments will be made: lean mass, myosteatosis, sarcopenia, adipose compartment, inflammation, micro RNA, food consumption, membrane phospholipid composition, composition of the intestinal microbiota, toxicity, response to antineoplastic treatment and survival.

Inclusion Criteria:

• Diagnosis of non-small cell lung cancer, both sexes, ECOG performance status (0-2) eligible for treatment with immunotherapy, chemotherapy and tyrosine Kinase Inhibitors.

Exclusion Criteria:

• supplementation of PUFA n-3 in the last 6 months; weight loss> 10% in 6 months, chronic liver disease, previous chronic kidney disease, anorexia, decompensated diabetes mellitus and dementia.

Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)