Presumably the documentary series?

It's probably more of a spectrum... some of what the treatments they talk about probably work very well... and some not as well.

Many of the treatments they highlight are being used and promoted by doctors, scientists and specialists all over the world. These people are all putting their personal credibility on the line by promoting these things... so they must believe they work... and they're much better positioned to judge the efficacy of a treatment than a member of the general public.

Not all treatments are useful for all patients... so it's unreasonable to expect 100% success rates with anything? Cancer cure rates are quite low when using chemotherapy or radiotherapy... which is why targeted cancer therapies are so attractive. New therapies only have to be equally effective or slightly better to be a better option? The big advantage of most targeted cancer therapies is that they are usually not toxic.

If you are inclined to try an alternative therapy make sure you match the proposed therapy to your cancer and check if there is some research validation? Some of these therapies are in clinical trials... which is generally a good sign.

Ideally you want some way to rank the effectiveness of the proposed therapy compared to other therapies. That's probably the hardest thing to establish... as success rates are often quite hard to obtain. Disappointingly conventional treatments also rarely provide success rates... or side effects making it very hard to make an informed choice.:-)