Induction Chemo-Nivo in Unresectable Stage III NSCLC

3 cycles of the proposed nivolumab + platinum doublet (either pemetrexed + carbo/cis or paclitaxel + carbo or docetaxel + carbo/cis for non squamous; or gemcitabine + carbo/cis or paclitaxel + carbo or docetaxel + carbo/cis for squamous) will be administered then CT and biopsy, followed by surgery with option for post-op NIVO-XRT, then 12 cycles NIVO at 480 mg IV every 4 weeks for 12 weeks

Participants will receive NIVO at 480 mg IV every 4 weeks for 12 cycles after either surgery or treated with concurrent chemotherapy-nivolumab-radiation

Induction Chemo-NIVO x 3 cycles then CT and biopsy, followed by surgery in patients whose tumors were unresectable stage IIIA-C at baseline on the basis of lymphadenopathy and are determined to be resectable after responding to induction chemotherapy-nivolumab. The participants have an option for post op XRT, then will receive NIVO at 480 mg IV every 4 weeks for 12 cycles

Induction Chemo-NIVO x 3 cycles then CT and biopsy, followed by concurrent Chemo and Nivo XRT (60Gy). Participants will receive concurrent thoracic radiation therapy using a standardized 3DCRT or IMRT technique on a linear accelerator operating at 2:6 MV beam energy. The target total dose of thoracic radiation therapy will be 60 Gy in 30 daily fractions of 2 Gy prescribed to the PTV. The participants then will receive NIVO at 480 mg IV every 4 weeks for 12 cycles.