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Cancer patients using complementary meds die sooner

But lower five-year survival rate is mediated by delay or refusal of conventional cancer treatments

Louise Prime

Monday, 23 July 2018

People with cancer who received complementary medicine were much more likely to refuse other conventional cancer treatment, and also had a greater risk of death compared with those who used no complementary medicine, US research has shown. But the authors behind the study*, published in JAMA Oncology, said this survival difference was mediated by adherence to all recommended conventional cancer therapies. They urged doctors to be proactive in discussing complementary medicine with their patients, given patients’ hesitance to disclose non-medical therapies, and to strongly advise “timely adherence to all recommended conventional therapies” in people with curable cancers.

The researchers, from Yale School of Medicine, pointed out that there is only limited information on the associations between complementary medicine (CM), adherence to conventional cancer treatment (CCT), and overall survival of patients with cancer who receive CM compared with those who do not receive CM. They examined overall survival between patients with cancer receiving CCT with or without CM; and adherence to treatment and characteristics of patients receiving CCT with or without CM.

Their retrospective observational study used data from the National Cancer Database for a cohort of 1,901,815 patients (258 patients in the CM group and 1 901 557 patients in the control group) from across the US who had been diagnosed with nonmetastatic breast, prostate, lung, or colorectal cancer over the decade from 1 January 2004. They matched patients by age, clinical group stage, comorbidity, insurance type, race/ethnicity, year of diagnosis, and cancer type; and then conducted their main statistical analysis of 258 patients in the CM group, and 1032 patients in the control group.

They reported that although patients who chose CM did not have a longer delay to initiation of CCT, they had significantly higher refusal rates of surgery (7.0% vs 0.1%), chemotherapy (34.1% vs 3.2%), radiotherapy (53.0% vs 2.3%) and hormone therapy (33.7% vs 2.8).

Use of CM was associated with poorer five-year overall survival compared with no CM (82.2% vs 86.6%) and was also independently associated with greater risk of death (hazard ratio, HR 2.08) in a multivariate model that did not include treatment delay or refusal. However, when the researchers included treatment delay or refusal in their model, they found no significant association between CM and survival (HR 1.39). Because of this, they surmised that the mortality risk associated with CM was mediated by the refusal of CCT.

Cancer Research UK commented that there are “a couple of important factors to consider” with this study – first, that people might not have told their doctors about their use of CM; second, that CM therapies vary significantly, so that “standardising them is tricky”; and third, that because recording the use of CM isn’t common, the study included only a small number of people who used additional treatments.

The study authors concluded: “We believe our work to be critically important to patients considering CM – a group that likely includes most patients with cancer. Given the hesitance on behalf of patients to disclose nonmedical therapy to their clinicians, health care professionals need to be proactive in discussing CM and adherence to conventional medicine treatment with their patients. For patients with curable cancers who are inclined to pursue complementary treatment methods, timely adherence to all recommended conventional therapies should be strongly advised.”

*Johnson SB, Park HS, Gross CP, Yu JB. Complementary medicine, refusal of conventional cancer therapy, and survival among patients with curable cancers. JAMA Oncol. Published online July 19, 2018. Doi:10.1001/jamaoncol.2018.2487

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