The main purpose of this study is to explore the PK/PD changes of NMN and DC cells after oral NMN combined with DC cells injection in patients after tumor surgery, and evaluate the biological age of adults, TCR diversity, SiRT1 expression level, SF-36 quality of life, OS, antigen specific immune response (TAA), cytokines and so on. In this study, 20 postoperative tumor patients who meet the entry and excretion criteria were recruited to explore the clinical potential of NMN combined with DC cell vaccine.

Inclusion Criteria:

• 1. 18-80 years old, weight ≥ 40kg.
• 2. Patients with malignant solid tumors diagnosed by histology or cytology, who underwent radical resection and completed standard postoperative adjuvant therapy.
• 3. Estimated survival time ≥ 6 months.
• 4. ECOG score 0-1.
• 5. Adequate venous channels, there is no contraindication for peripheral blood monocyte collection.
• 6. Good function of organs and bone marrow.

Exclusion Criteria:

• 1. Diabetes.
• 2. Premenopausal or menopause <1 year.
• 3. Persons who have received hormone replacement therapy within the past 6 months.
• 4. Persons who take vitamin B supplementation and are not willing to discontinue supplementation for 3 weeks before and during the entire study period.
• 5. Unstable weight (>3% change during the last 2 months before entering the study).
• 6. Significant organ system dysfunction or disease.
• 7. Polycystic ovary syndrome.
• 8. Major psychiatric illness.
• 9. Use of medications known to affect study outcome measures (e.g., steroid) or increase the risk of study procedures (e.g., anticoagulants) that cannot be temporarily discontinued for the study.
• 10. Metal implants.
• 11. Persons who consume >14 units of alcohol per week.
• 12. Unable or unwilling to follow the study protocol or who, for any reason, is considered an inappropriate candidate for the study by the research team.