So sorry about your father's cancer.
I'm not selling or promoting anything for profit.
Eight grams of curcumin in 4 divided doses (every 6 hours) has actually proven to cure cancer. The FDA even agreed with this.
You should use something with guaranteed curcumin content like "Yarrow Curcumin 95". Take it with Bio-perene. This black pepper extract intensifies the effects of curcumin. This is not always without side effects but you have to battle through them. I get horrendous head aches.

In addition your father needs to get his body PH to 7.0 and keep it there. Since he can't eat well I would suggest using Alka-Seltzer GOLD 3-4 times a day. That's Gold NOT Cold. The Gold contains bicarb and potassium salts. You should use PH test strips to check the PH of his urine 2-3 times a day to know how to adjust dosage. Never put the test strip in your mouth. There are chemicals in the strip that are dangerous. The mouth will not give a true reading anyway.

If you can get Mebendazole (Ebay-India or China)he should take the recommended dosage daily. This drug was on the market in the US for treating pin worms but when they discovered it STOPPED cancer they stopped making it. I imagine it will reappear some day as a miracle cure. But they still make it in India. If you can't get it or there is a long delay in receiving buy Panacur horse paste at a farm store. Depends on his weight, but spread the dosage out over 3-4 doses a day. It works about the same as Mebendazole.

If you have the money buy a Rife Zapper. There are numerous frequency runs for treating cancer. I can tell you from experience that zappers actually work but you need to be careful about what you buy. Walk away from the "Hard Sell" they are just hype. I use a Rife zapper I purchased on the web.

There are numerous other things that help but you need to stop the spread NOW.
-folate 4 times a day....NOT folic acid
-Solgar liver Cleanse.....dirty livers contribute to cancer
-Iodine....Iodoral is expensive but easy to use. Start low and work up to 100MG as fast as he can take it.
-Solgar Ester Vit C. Buy capsules because he can't break down pills. Have him take as much as he can tolerate in 4 divided doses up to a total of 8 Grams daily. (I take more but 8 is the commonly recommended cancer dose) Take the Vit C with Thiamin- high dose again (I take 3 grams). This C plus Thiamin formula was used for decades to cure sepsis (blood poisoning)
-Doxycycline Antibiotic has proven to kill cancer. If you get a script it will cost 3-5 US dollars a pill. If you buy from a pet supply or ebay you can get it for about $1 per 100MG. I have not found what dosage is recommended for cancer but I would suggest at least 100mg 4 times a day.

This is just a start. Most importantly..."Attitude is Everything". If he would practice visualizing the cancer disappearing this will encourage his body to heal. This is not snowflake BS. It works.

Hoping for the best for you and your father. My mother refused to listen and died quickly. Everyone thinks Doctors are the answer. The body was designed to heal itself given the appropriate support.

Are you new to alternative or integrative medicine?

There are some amazing recovery stories out there, for example

Stage-4 Cancer in abdomen Cured in 7 Weeks without Chemo-- Removed Root Canals.
https://www.youtube.com/watch?v=LLgNhOTYGHI

If you are wealthy you can go to one of the cancer clinics in Mexico.

Bailey went to Mexico after mainstream failed
https://www.youtube.com/watch?v=YFyqX9Nmbj8
https://www.youtube.com/watch?v=6tRhkYQ9q-g

Hope4cancer is 1 block from the beach but has been around for quite some time. You'll learn more here.
https://www.cancerdefeated.com/videos/
https://www.youtube.com/watch?time_continue=1532&v=rjYSruBOXy4

Hoxey Biomed is supposedly one of the less expensive options in the Tijuana area. They have one of the most amazing recovery stories I've come across. TheTruthAboutCancer.com did an interview with D Olsen but I don't think it is online. This is the summary of his case http://www.hoxseybiomedical.com/patient-testimonials/

Some folks go to Nevada where integrative doctors have their own medical board and so are not harassed by mainstream guys.
https://www.youtube.com/watch?v=zyLGe69SqVs
https://www.youtube.com/watch?v=vAl8rjTls7M
https://www.naturalhealth365.com/cancer-integrative-medicine-2389.html

Hopefully you can work with an integrative oncologist in your area. If you can't find one, maybe one of the health coaches can help you find one. https://www.chrisbeatcancer.com/module1

If you are really short on $ and ability to travel...
https://www.cancertutor.com/dirtcheapprotocol/

Stage 4 protocol
https://www.cancertutor.com/advtreatments/

I assume you'll need to learn about juicing asap.
https://www.cancertutor.com/?s=juicing

Vitamin D seems to be a must! If he doesn't get outside in sunlight, he'll probably benefit from 5000IU but testing is not expensive and his doc might allow insurance to spring for it.
http://www.chrisbeatcancer.com/vitamin-d-the-1-anti-cancer-vitamin/

Other members provided good leads too.

If you tell us where you live, members might have tips for finding an integrative oncologist.