Stage IV Non Small Cell Lung Cancer Treatment for Dad - going forward

Dad (80 years old) is suffering from Stage IV Non Small Cell Lung Cancer (one smallish primary tumour in lung), and 2 very small secondaries; in liver and on spine. It was detected at that Stage 16 months ago. He has had chemotherapy, maintenance chemotherapy, and now high dose palliative radiotherapy here in the UK, and is performing very well. The scan 3 months ago showed further growth of his primary after having a break from maintenance permetrexed, and we are awaiting results of recent radiotherapy. 

I'm just writing this post to see if anyone has any suggestions or similar experiences for this stage and type of cancer. What to do next in terms of treatment? 

Here are my main concerns: 

(1) Dad has had liver cirrhosis in the past, and when they first of all found a liver cancer, they thought it was as a result of the cirrhosis which is likely. When he went for treatment of it, they said not to worry, as liver tumour seemed to be inactive and he wouldn't need to worry about it for a few years. Later, when they found he had lung cancer, the liver specialists were confident the liver cancer was not related to the lung cancer. However, when this was passed onto the LUNG cancer team for treatment, they assumed liver cancer was only a met (secondary) of the lung cancer. This has always puzzled me, as he's doing very well 16 months after diagnosis, his primary tumour was relatively small, and his mets have never grown at all for 16 months. I was wondering if it was a possibility that it is not actually Stage IV lung cancer after all and separate primaries?

(2) Dad's had first line chemo with Carboplatin + Pemetrexed (4 sessions) after which there was a significant reduction of 30%. He then went on to maintenance Pemetrexed after which the cancer did not grow for 6 months. Then he stopped for a 6 week break, and his next scan showed a fair bit of growth so we stopped the maintenance perm and went on to high dose palliative radiotherapy. Awaiting results now.  But what are suitable treatments going forward, given he is in top performance and doing very well - almost like he's never been ill. He is a fighter and would not be someone to sit around without treatment. He has had minimal side effects to all treatment so far and his performance has been A1. Some options I thought about are:

(a) Second line chemotherapy - Docetaxel was suggested by one consultant but main consultant was worried the risks might outweigh minimal benefits which is when they opted for radiotherapy instead.

(b) His insurance might cover him for drugs such as Bevazicumab if radiotherapy has not worked.

(c) His hospital has started trials of Pembrolizumab - which was recently on news as having remarkably reduced people's Non Small Cell Lung Cancer by up to 50% - but worried about his other health problems (liver cirrhosis) etc. 

Any other suggestions or questions to ask the Consultant at his next consultation would be very welcome.

Thank you very much 

John 

p.s. I've included his full history below in case you're interested: 

Patient history:

May 2013 Dad presented some symptoms as a result of lung cancer (preicardial effusion), and then a pleural effusion in August 2013, when he was diagnosed with Stage IV Non-small cell lung cancer (Adenocarcinoma. EGFR/KRAS both wild type. ALK not translocated. Stage at presentation: T2a N3 M1b). He also was then found with a met in the liver (small) and 2 on the spine (small). Initially, they thought it was liver cancer. The liver specialists said it had no relation to the lung cancer as he has a history of liver cirrhosis. However the lung cancer doctors say the liver mets are as a result of lung cancer, as are the spine. No biopsy of liver or spine mets done to date. Primary tumour size initially: 4.2cm x 3.0cm

August 2013 he then he suffered a pleural effusion which stopped after drainage and never returned. 

September 2013 front line chemotherapy commences. 4 x 3 weekly intervals of Carboplatin + Pemetrexed.  30% reduction in tumour after 4 sessions. Primary tumour size now: 3.9cm x 2.3cm

December 2013. Starts maintenance chemotherapy with Pemetrexed only. No change in size to primary tumour for 6 months. 

March 2014. He then took a long break (6 weeks) from maintenance Pemetrexed. It was at his next scan in June 2014 after the break that the primary was found to have grown, Tumour size now: 5.5cm x 4.7cm.  The family were worried that stopping the 3 week pattern of maintenance might have resulted in this growth. 

July 2014. Dad then starts high dose palliative radiotherapy. 

September 2014. We are awaiting scan results to see how the palliative radiotherapy has done, but his performance is, and has always been A1. 

 John