My mother has had both chemo and radiotherapy and was not advised against taking caffeine....she drank her usual quantities of tea or coffee, if not more, during her treatments. This is the first I've heard of it not being allowed to be consumed with the above treatments.
With regard to DCA....it is not recommended that the DCA be taken "in" tea/coffee as it is unstable in hot or warm substances. The B1/caffeine protocol just encourages increased intake of caffeine and tea has been used successfully. The DCA should be taken in a cool substance, i.e. water, juice etc. (iced tea would be OK)
My mother was diagnosed with rectal cancer with lesions in the lungs and liver as well as in one of her vertebra. She underwent surgery to remove the rectal tumour and now has a colectomy (bag to collect stool). She underwent radiotherapy prior to the surgery to apparently shrink the tumour, although we never learnt if it did or not! She has recently had chemotherapy, however it had to stop due to her developing some heart problems, which they attributed to the chemo. My mother is 73 and I've encouraged her to use DCA, which initially she was very keen to do. However, she decided to proceed with "conventional" treatments and to only take DCA if all else failed....as disappointed as I am with her decision, it is hers to make.
At this point in time her oncologist has suggested she discontinue treatment for a period of three months to assess the progression of her tumours. Chemotherapy is no longer an option, although he mentioned another type that isn't as good but a possibility for later on.
It is now that I am encouraging my mother to start the DCA again. She has been very weak and tired since having the surgery and other treatments and I think she hopes to regain some strength before she tackles the DCA.....I also believe her mental health deteriorated significantly on the day of her diagnosis...she is quite depressed and has severe anxiety attacks now...something that never occurred before.
I'm telling you all this because I thought my experience might assist you and also let you know that someone else on this site has the exact same disease.
I would encourage your father-in-law to start the DCA as soon possible. If he is able, get him to read some of the testimonials of people who've had success.
Most people using the DCA don't have approval of their medical carers so this site offers so much help with regard to dosage, supplements etc. I find it invaluable. Read as much as you can on the site (it will take days!!)and you will learn so much! The trick then is relaying the info to your father-in law.....
Please remember that every person is different - treatments can be amazingly successful for some and not helpful at all for others. However, there is a lot to lose if you don't try something and DCA appears to offer success in so many people that I believe it is worth a shot!
Wishing you, your father-in-law and family great strength and a smooth road ahead....it is a daunting time and I so understand what you are going through right now.....