Inclusion Criteria

Inclusion Criteria - Registration:

- Histological diagnosis of NSCLC. Histology can be either squamous or non-squamous.

- Stage IIIB or stage IV lung cancer that is not amenable to curative therapy.

- ECOG performance status 0-1.

- Have had no prior systemic treatment for lung cancer including previous adjuvant
and neoadjuvant therapy. Patients who have already started their chemotherapy are not
eligible.

- Eligible to receive standard platinum doublet-based chemotherapy.

- Men or women, aged 18 or over and capable of giving informed consent.

- Willing to consent to provide tissue and blood for translational research.

- Informed consent prior to any study specific procedures.

Exclusion Criteria - Registration:

- Evidence of small cell, large cell neuroendocrine or carcinoid histology.

- Have a serious or uncontrolled medical condition that could compromise the patients'
ability to adhere to the protocol.

- Have a secondary malignancy (except adequately treated non-melanomatous skin cancer,
or other cancer considered cured by surgical resection or radiation). Patients who
have had another malignancy in the past but have been disease free for more than 5
years are eligible.

- Have had a blood transfusion within 4 weeks prior to study entry, and have a white
blood count >3x109/L.

- Have central nervous system metastases (unless the patient has completed successful
local therapy for central nervous system metastases).

- Are receiving concurrent administration of any other systemic antitumour therapy.

- Have received a recent (within 30 days of enrolment) or are receiving concurrent
yellow fever vaccination.

- Previous treatment with PARP inhibitors.

- Difficulty swallowing.

- Uncontrolled GI disorders such as active diverticulitis or colitis, or any major GI
resection which could have an impact on patients' ability to absorb Olaparib.

- Patients with myelodysplastic syndrome / acute myeloid leukaemia.

- Congenital long QT syndrome.

Inclusion Criteria - Randomisation:

- Partial or complete response to platinum containing doublet chemotherapy after a
minimum of 3 cycles, according to RECIST, as assessed by the local radiologist.
Patients with stable disease or a mixed response following induction chemotherapy
should not be included.

- Adequate organ function, including the following:

1. Adequate bone marrow reserve; absolute neutrophil count (ANC) >1.5 x 109/L,
platelets >100 x 109/L, Haemoglobin of >10g/dl.

2. Hepatic: total bilirubin <1.5 times the upper limit of normal (xULN); alkaline
phosphate (ALP), aspartate aminotransferase (AST) and alanine aminotransferase
(ALT) <2.5 x ULN. ALP, AST and ALT <5 x ULN is acceptable if the liver has
tumour involvement.

3. Renal: calculated creatinine clearance (CrCl) >50ml/min based on the original
weight based Cockroft and Gault or Wright formula, serum creatinine <1.5 x
institutional ULN.

4. No features suggestive of myelodysplastic syndrome/acute myeloid leukaemia on
peripheral blood smear.

- Willing to use two adequate forms of contraception throughout the trial and for three
months following last administration of olaparib.

- Informed consent.

Exclusion Criteria - Randomisation:

- Patients with radiological disease progression or stable disease.

- Have received treatment with an agent that has not received regulatory approval,
within 30 days of study entry.

- Have had a blood transfusion in the period between induction chemotherapy and
starting Olaparib dosing and have a WBC >3 x109/L.

- Resting ECG with measurable QTc >/- 480 msec.

- Are pregnant or breastfeeding.