The goal of the investigators study is to investigate the role of a hormone named Activin A (ActA) in the development of the skeletal muscle atrophy caused by cancer. According to the investigators hypothesis, ActA could be released by the tumor and activate a muscle atrophy gene program. To answer this question, the investigators plan first to compare circulating levels of ActA in cancer patients with and without cachexia. In a second step, the investigators would like to assess whether ActA circulating levels are predictive for the development of cachexia and short survival.

Inclusion Criteria:

• 18-year-old or older
• Colorectal or lung cancer demonstrated by histology or cytology
• New diagnosis or new recurrence
• Expected survival more than 3 months
• No previous history of other cancer in the last 5 years
• No pregnancy or lactation
• Signed informed consent

Exclusion Criteria:

• Non-caucasian
• Major digestive malabsorption
• Major depression
• Artificial nutrition
• Height doses of steroids (>1 mg/kg hydrocortisone equivalent)
• Hyperthyroidism
• Other causes of malnutrition
• Expected survival less than 3 months
• Severely impaired walking
• Anticoagulants or antiplatelet therapy
• Disability or medical condition which might prevent the compliance to the protocol
• Any conditions which may prevent the compliance to the protocol
• Performance status ECOG > ou = 4
• Participation to other clinical studies