My father has been diagnosed with Non-Small Cell Lung Cancer, Stage 4 with primary tumour in his Left Upper Lung and metastasis in Liver and Bone. The biopsy report has confirmed it to be adenocarcinoma. The cancer was detected while he was admitted at a hospital in Mumbai and was undergoing treatment for Acute Paraplegia which happened on 02 Nov 16, due to arteries-Venous Fistula at D-10 level resulting in oedema/ ischemia of the spine from D-5 to Conus. After two failed attempts of embolization, towards treatment of the AVF, surgical clipping of the fistula was undertaken on 10 Nov 16. As part of post-operative rehabilitation therapy for his paraplegia, he was given 65 session of Hyper-basic Oxygen Therapy at 2.4 ata pressure for about two and a half month and about two hour of Physiotherapy for the same duration. My father was recovering well and had started walking with the help of support (walker). MRI of the spine taken in mid Jan & Mid June 2017 indicates that the spinal cord oedema had improved significantly, although atrophy of the spine cord is still present. He complained of wheezing and breathing difficulty and towards ascertaining the cause a X-ray was taken on 23 Feb 17 which showed massive pleural effusion in his left lungs. A series of tests followed with the ultimate result as NSCLC Stage 3B. He was started with CCRT treatment which concluded on 05 May 17. During the treatment he was given daily dose of radiation therapy using IGRT (60 Gy/ 30 #/6 weeks) and weekly chemotherapy with paclitaxel (150 mg) & Carboplatin (300 mg) for 6 weeks. Despite the treatment, the cancer is advancing and has now spread to Liver and Bones as brought out in his latest PET CT report. Lung tissue which was obtained during CT guided biopsy conducted in the month of Mar 17, before the CCRT treatment was started, has tested positive for EGFR mutation ? ?E746_A750del is detected in EXON 19 of EGFR gene?. The medicine oncologist has however said that the gene profiling of the primary tumour tissue is not sufficient for starting Targeted Therapy and gene profiling of a tissue obtained from any of the metastatic site is necessary for the same. Three procedures have been undertaken to obtain tissue sample from the metastases site, twice from the liver and once from the pleural deposits, and all the three times the cancerous tissue could not be obtained. Due to non-availability of conformed cancerous tissue from the metastases site, a firm treatment plan has yet not been made for my father. In the meantime, the doctor has recently started my father on Erlotinib 150 mg OD as there has been considerable delay in his next phase of treatment due to non availability of metastases cancerous tissue. Could you please help me by answering the following:- 1.Can you suggest anything towards treatment of my father? 2.Is gene profiling of tissue from a metastases site absolutely necessary for starting targeted therapy for my father? 3.I read online that Erlotinib or Afatinib can be used as Targeted Therapy for patient with EGFR Lung cancer mutation. Is this true? If yes, will a daily tablet of these drugs be sufficient for his next phase of treatment, or a concurrent conventional chemotherapy is also required? 4.Can 65 session of Hyper-basic Oxygen Therapy at 2.4 ata given at a stretch of about 80 days, with a daily dose of 02 hour be a cause of his cancer? I have read it online that the oxygen free radical produced during HBOT treatment can cause cancer.