Limonene for Pulmonary Nodule Chemoprevention

Inclusion Criteria:

• Non-smokers (those who have smoked less than 100 cigarettes in their lifetime,including those who have never smoked in their lifetime).
• Subjects must have positive nodules detected by high-resolution CT（HRCT）: longestdiameter > 6 mm and < 20 mm; pure ground glass nodule; according to the judgment ofthe clinician, follow-up can be performed, and surgical excision is not recommendedfor the time being; the nodules did not disappear or were not significantly reduced bymore than 2 mm after six months follow-up; subjects should have at least one positivenodule when had multiple nodules.
• ECOG performance status 0-1.
• Those who accept and are willing to sign the informed consent.

Exclusion Criteria:

• Subjects with the history of autoimmune diseases and severe gastrointestinal diseases;
• Subjects suffering from malignant tumor, severe heart disease, severe liver or kidneydisease currently or within the past 5 years;
• Within 6 weeks since prior herbal supplements, non-steroidal anti-inflammatory drugs,or antibiotics
• Subjects who are allergic to limonene capsules or citrus foods;
• Use of any other investigational agents at time of enrollment in the study during thethree months preceding study enrollment
• Pregnant or lactating females, or those who disagreeing with contraception;
• Subjects who have a history of mental illness and cannot cooperate with this project;
• HIV-positive subjects should be excluded.
• Subjects whose organ and bone marrow function indexes exceeded the following range ofnormal value were excluded:

1. Leukocytes: 3.5-9.5 109/L;
2. Absolute neutrophil count: 1.8-6.3 109/L;
3. Platelets: 125-350 109/L;
4. Total bilirubin: 5.0-21.0 µmol /L;
5. AST (SGOT)/ALT (SGPT): 0.8-1.5;
6. Serum creatinine: 41-81 μmol/L;

• Other situations where the researcher thinks it is inappropriate to participate inthis research.