Based on this hypothesis the investigators intend to do a pilot phase II study of histology based consolidation chemotherapy in patients with inoperable stage III NSCLC following concurrent chemo-radiotherapy. Patients with inoperable stage III NSCLC would be treated with standard concurrent chemo-radiotherapy and subsequently those with non-squamous histology would be offered 4 cycles of consolidation pemetrexed and those with squamous histology 4 cycles of consolidation with gemcitabine.