Finding out you have cancer can be a huge shock. There’s a million questions to ask and a hundred decisions to make. That’s why it’s important patients have the best advice, based on accurate information, when thinking about their treatment options.

But it doesn’t take much digging online to find things that claim to help tackle your cancer while seeming less daunting than conventional medical treatment.

These non-medical therapies taken alongside conventional cancer treatments, such as herbal medicines or aromatherapy, are called complementary therapies.

Dr Skyler Johnson, a radiation oncologist from Yale University in the US, says he’s seen his own patients being drawn to complementary treatments. According to Johnson, it’s common for people to think that these additional treatments can boost survival.

“There’s really no evidence that supports people’s beliefs that complementary medicine can improve survival,” says Johnson.

There’s really no evidence that supports people’s beliefs that complementary medicine can improve survival.

– Dr Skyler Johnson, Yale University

And a new study from Johnson and his team, published in the Journal of the American Medical Association, attempts to measure what the impact of complementary medicine might be.

The results suggest that people who had complementary therapy for treatable cancers were more likely to opt out of at least one part of their conventional cancer treatment. And they were more likely to die as a result.

“Some medical professionals, ourselves included, thought when a patient comes in and says they want to try a complementary medicine instead of a conventional cancer treatment we could convince them to do both,” says Johnson. “It seems like a good compromise and we thought they’d still do just fine.”

But unfortunately, there’s no evidence to support these assumptions. “That’s why we felt it was important to do this study.”

How did the study work?

The team looked at patient records from the vast US National Cancer Database. They picked out patients who had been diagnosed with the four most common types of cancer (breast, lung, prostate and bowel cancer) between January 2004 and December 2013. These patients had cancer that was deemed treatable with conventional cancer treatment.

They then selected all the patients whose records said they’d chosen to have a complementary treatment with at least one additional conventional cancer treatment such as surgery, radiotherapy or chemotherapy. Out of almost 2 million people diagnosed in this time period only 258 had a written record that they’d opted for a complementary treatment.

These 258 people were then matched with others in the sample who hadn’t received additional treatments but shared similar factors, like cancer type, cancer stage and age.

“These are the features that impact survival,” says Johnson. “It meant we could eliminate these confounding factors that would otherwise impact the results.”

After analysing the data, it appeared that both groups started their recommended conventional treatment at a similar time. But those who chose to use complementary therapies were more likely opt out of additional medical treatment further down the line.

Impact on survival

The team then compared the overall survival of the two groups.

“The results say that cancer patients who chose to use complementary medicines in addition to conventional cancer treatment were at an increased risk of death,” says Johnson.

The results say that cancer patients who chose to use complementary medicines in addition to conventional cancer treatment were at an increased risk of death.

– Dr Skyler Johnson, Yale University

Crucially, they found that the risk of death was even more significant for the people who thought they could use complementary treatments to replace part of the treatment recommended by their doctor.

“Most people are combining complementary treatments with conventional cancer treatments thinking that it was the best of both worlds,” says Johnson.

He’s concerned that patients are choosing their treatments “à la carte”, thinking they can pick the conventional cancer treatment that’s most palatable and supplement this with a non-medical treatment that doesn’t have the side effects of chemotherapy, for example.

“From the data it looks like most patients in the complementary medicine group had surgery but were more likely to turn down radiotherapy and chemotherapy.”

The study didn’t find out why. It just showed that in general these patients didn’t do as well as their matched counterparts.

Reading between the lines

Patients in the complementary medicine group were more likely to be younger than those who didn’t have complementary medicine. They were more likely to be female, have breast or bowel cancer and be from a wealthier background with higher levels of education.

This is similar to a study Johnson published last year looking at the impact of alternative therapies on cancer survival.

“One of the very nuanced and interesting parts of this study is that this young female group, who in general have a lower cancer risk and a better chance of survival if they do develop cancer, were more likely to use complementary medicines.”

The study showed taking these additional treatments didn’t impact their survival.

“However, in theory, if complementary medicine were to boost survival, then this group taking complementary medicine should be doing better than those who aren’t.”

But that wasn’t the case.

Possible limitations

Even though this study suggests a link between the use of non-medical cancer treatments and a lower chance of survival, there are a couple of important factors to consider.

First, the study relied on people telling their doctors if they received additional non-medical treatment. “The reality is that patients aren’t always telling their doctors the decisions they’re making and what they’re doing,” says Johnson. So it’s feasible that some patients in the group that were badged as only having conventional cancer treatment may have used non-medical therapy too.

Second, the types of complementary medicines people take vary significantly and standardising them is tricky. This study defined a complementary medicine as “an unproven cancer treatment administered by non-medical personnel”, which could range from a complex mix of herbs to Chinese medicine or a vitamin supplement.

Finally, because recording the use of complementary medicines isn’t common, the number of people who the team could be sure used additional treatments was small. Comparing a bigger group of people would provide a more accurate picture.

What didn’t the study show?

Johnson says he can’t speculate as to why people decided to use these additional treatments. “This study quantifies for us who’s doing what and how often they are doing it and what is the results of those decisions.”

There’s nothing now that can suggest why people are choosing to skip conventional treatment for a complementary one.

This is something the team want to look into next. “I think in the future we’ll need to tease out some of the behavioural aspects of this,” he says.

Making up your own mind

Martin Ledwick, Cancer Research UK’s head information nurse, stresses that the patients in this study had cancers that could be treated with conventional treatments.

It is important that patients considering complementary therapies do not see them as an alternative to conventional treatments that have been shown though clinical trials to make a real difference to survival.

-Martin Ledwick, Cancer Research UK

“It is important that patients considering complementary therapies do not see them as an alternative to conventional treatments that have been shown through clinical trials to make a real difference to survival,” says Ledwick.

“In this study people with potentially treatable cancers who delayed or refused conventional treatments while they tried complementary approaches had a greater risk of dying.” He says it’s important that people are now made aware of this.

The next task for Johnson is to work out what information people value and then think about how this information is presented in a way to help people make an informed decision.

Ledwick agrees and says patients need support to fully understand what can be expected from conventional treatments and to be aware of “the significant risk of substituting these with unproven therapies”.

Patients have the right to make their own decisions about treatment, but that should come with clear information on what the impact of that decision might be. This study helps make part of that story clearer.



Johnson, S. et al. (2018) Complementary Medicine, Refusal of Conventional Cancer Therapy, and Survival Among Patients With Curable Cancers. JAMA Oncology. DOI:10.1001/jamaoncol.2018.2487