Icotinib in Previously Treated Non/Light-smoking Patients With Advanced Squamous Cell Lung Cancer

Inclusion Criteria: * Histologically or cytologically confirmed metastatic or recurrent squamous cell lung cancer from the primary lesion and/or lymph nodes, stage IIIB or IV patients with non-smoking or light-smoking history. * Failure of at least 1, and no more than 2, prior chemotherapy regimens for advanced disease (either due to progressive disease or toxicity). * Have measurable disease, defined as at least one lesion that can be accurately measured in at least one dimension (longest diameter to be recorded) as \>= 20 mm with conventional techniques or as \>= 10 mm with spiral CT scan. * Be \>= 18 years of age. * Expected survival period over 12 weeks; * ECOG PS 0-2. Adequate organ system function as defined within the protocol. * Patients with a history of CNS metastases or cord compression are allowed if they have been definitively treated and are clinically stable. * Consent compliance research plan and follow-up process, and be able to carry out oral therapy; Provision of written informed consent. * In women of childbearing age, must be in before starting treatment within 7 day of urine pregnancy test and the result is negative, and not in the lactation period, and reproductive age men and women prior to entry into the study, the research process until 90 days after stopping all agree to use reliable methods of contraception; * Weight loss =\< 10% in past 6 months. * Adequate tumor tissue for detection of molecular biomarkers. Exclusion Criteria: * Patients who have previously received treatment with EGFR-TKIs. * Concomitant treatment with any other experimental drug under investigation or anti-tumor therapy; * Symptomatic CNS metastases or newly diagnosed CNS metastases that have not yet been definitively treated with radiation and/or surgery. * Known severe hypersensitivity to icotinib or any of the excipients of this product. * Presence of uncontrolled pleural effusion or/and peritoneal effusion; * Evidence of any other significant clinical disorder or laboratory finding that makes it undesirable for the subject to participate in the study. * Past or current history of neoplasm (other than the entry diagnosis) in past 5 years, with the exception of treated basal cell carcinoma or carcinoma in situ of the cervix, or other cancers cured by local therapy alone. * Women who are lactating.or have positive pregnancy test.