For cancer patients wanting to use legal marijuana, it can be tough to find reliable information. So I asked Dr. Jordan Tishler, who runs medical offices in Cambridge and Brookline dedicated to prescribing cannabis, some basic questions about cannabis and the advice he offers his patients.

His comments have been lightly edited for clarity and length.

Is there enough research to conclude that medical cannabis can be helpful for cancer patients?

It’s inarguable that we could always use more data. Is there enough that we could make a reasonable decision now? The answer is clearly yes.

How could a cancer patient benefit from using cannabis?

Nausea and vomiting, appetite issues, fatigue, anxiety, insomnia -- those sorts of things that are associated either with cancer or chemotherapy, those things are very well treated with cannabis.

There has been a small amount of research suggesting that cannabis can also help treat cancer. What’s the state of that research? Is it believable?

We do not have enough information. We have some very beginning materials that are very encouraging and suggestive, but nowhere near the level we would expect if we started treating someone with any other medication.

Would you treat patients with cannabis instead of chemotherapy or other conventional treatments?

I’m very clear [with patients] that I’m not going to participate in this [care] if they are rejecting conventional treatment, but rather willing to participate in this as an addition to their treatment. Cancer patients who rely upon alternative medicines die more quickly than patients who use conventional therapy.

Do you see cannabis as an alternative to opioids?

Cannabis and opiates for moderate to severe pain really study out as being equally efficacious -- neither of them are super good. But the cannabis is much safer.

There’s clearly a place for opiates in our medical treatment regimen, but if you start with cannabis, maybe you don’t need to get to the opiates, or if you do you need to get opiates, we have really good data that you need a lot less. If you use cannabis and opiates together, you typically use only 20 percent of the amount of opiates you would have otherwise needed. With opiates, your risk goes up every time you increase [the] dose by a milligram. If you have someone who would need 100 mg of opiates, if you cut back to 20 mg, you’ve saved them 80 percent of the risk of the opiate. That’s huge.