HALIFAX -- As a cancer physician, Dr. Bruce Colwell hasn't just been dealing with the recent shortage of Tamoxifen, because it's not the only cancer drug in short supply across the country.

"We have struggled, there's been times when we have been quite short," said Colwell, who is also the president of the Canadian Association of Medical Oncologists. "We had to change the way we give it."

According to the official drug shortage website, there are three cancer drugs currently in short supply.

Two of them, chemo drugs vincristine and vinblastine, are not expected back in full supply until the end of January 2020. 

Another has been discontinued by some manufacturers.

The province's cancer care program says, even though there is a national shortage, there is supply in Nova Scotia.

"If you're a patient on it, they're always very important for you, so they are important, some of them are more critical than others," Colwell said.

Cancer patient Clyde Caldwell has been caught in the midst of a recent shortage of another cancer drug, which keeps his blood from clotting too much.

Right now, he has seven days' worth of his medication. Without it, his risk of stroke goes up.

"Without that drug, it's time to start planning the funeral," Caldwell said.

He's not sure he'll be able to get any more soon.

"I believe the drug companies just want us to switch to a more expensive drug," he said.

Colwell says that particular drug is no longer officially on the shortage list, so it may be on the way, but replenishing the supply chain takes time.

For physicians and patients alike, there is frustration in the fact that there is very little explanation given by companies when supplies run dry.

"And that's the problem that we struggle with a lot, is we have to react to something we have absolutely no control of," Colwell said.

It's something that needs to change, Colwell says, to end the ongoing uncertainty around Canada's drug supply and the uncertainty for patients who need their medications.