Since you don't know what type of cancer it is, you could direct your friend and his wife to Inspire, which has a number of communities on different types of cancer.

I've frequented that site for the last year, since my husband was diagnosed with a relatively rare lung disease. Some of the posters in my little area of the site are like those here — asking relevant questions, giving relevant answers, offering support as needed from a been-there-done-that-here's-what-worked-for-me perspective. Others take the name of the site more "seriously," writing intensely personal stories containing platitudes that, frankly, I don't find particularly helpful or inspirational (though I understand that others might). Unfortunately, it's the only site for his disease that has regular activity, based on frequency of postings -- there are other sites, such as Patients Like Me, but they appear to have a smaller patient/caregiver group and as a result have fewer postings.

I was spoiled when I stumbled upon OCF 10 (!) years ago and posted a ton of questions about what turned out to be a very, very early stage of SCC on my husband's tongue — and got the help, support and information that I needed. This is a special community, and I agree with Sophie's and Christine's assessment that there is no place like it.