By Keith I. Block, MD
UPDATED SEPTEMBER 26, 2011
Recently I received a flood of questions from concerned patients in response to a study published online on 12 September 2011, in the journal Cancer Cell. The findings reported by scientists at University Medical Center Utrecht in the Netherlands revealed a discovery of two fatty acid substances that can render cancer cells resistant to a specific type of chemotherapy.
But that wasn’t all they found. The Dutch researchers noted that these same fatty acids exist in at least some fish oil products. This latter finding has triggered a huge surge of consumer worry, since taking fish oil concurrently with chemotherapy is a common recommendation for physicians in the field of integrative oncology.
We’ve recognized for many years that people undergoing chemotherapy often respond less effectively over time, and many mechanisms have been identified to explain this unfortunate phenomenon. The Dutch team’s research indicates that chemotherapy is rendered ineffective, in part, by two types of fatty acids that are generated by stem cells in the blood. These fatty acids are specifically known as platinum-induced fatty acids, or PIFAs, because chemotherapy drugs that contain platinum (cisplatin, carboplatin, and oxaliplatin) all also trigger their production.
So here’s the bottom line of this discovery: When the human body is exposed to platinum-containing chemotherapy, stem cells in the body secrete the PIFAs, which in turn induce resistance to a broad range of other chemotherapy drugs (not just the ones listed above). In their experiments, the researchers isolated these fatty acids from the medium in which chemotherapy - exposed stem cells were grown. They then administered the PIFAs to mice and found that the chemotherapy drugs were ineffective against the mouse tumors.
As I alluded above, the scientists also found these same fatty acids in two commercial brands of fish oil supplements. After administering these same fish oil products to mice that had cancer, tumors were once again found to be insensitive to chemotherapy. This led medical oncologist Emile Voest, who helped supervise the Utrecht research team, to recommend that fish oil products (or algae oil) should not be used while people undergo chemotherapy.
There are several major problems with this line of thinking. First and foremost, this study must be put in its proper context. It is just one mouse study, and it is inconsistent with the lion’s share of human and animal evidence to date. There are at least 17 human studies that show benefits for cancer patients taking fish oil. Additionally, a new study last month specifically contradicted the Voest study, indicating an increased rate of response to chemotherapy for patients taking a platinum drug with fish oil.
In this new study of 46 advanced lung cancer patients received platinum-based chemotherapy plus either gemcitabine or navelbine. The chemotherapy response rate in the fish oil group (2.5 grams per day) was more than double that of the non-fish oil group (60% vs. 26%), along with a trend toward improved survival. These findings were reported in the August 15, 2011 issue of the prestigious journal Cancer. Additionally, given the wide margin of safety along with the various quality-of-life benefits obtained from using fish oil (e.g., reduced inflammation and better weight maintenance), this would seem to be a fairly strong reason for oncologists to recommend a fish oil supplement when treating advanced cancers.
Moreover, numerous lab studies (both animal and cell culture) demonstrate that fish oil and other omega-3 products actually reduce or may even reverse resistance to chemotherapy or increase sensitivity. The Dutch researchers acknowledge that when including either pure EPA or DHA or both fatty acids in combination, they showed no adverse effects on chemotherapy treatment (and, in fact, they used EPA/DHA exposure as their control group).
And it should be noted that since only two fish oil products were analyzed, the Dutch researchers are now moving ahead with research to determine whether other fish oil products also contain the PIFAs. Neither of the fish oil products analyzed in their published study was molecularly distilled, which is now the norm for almost any high-quality fish oil available in the marketplace. It is quite possible that there are no PIFAs in molecularly distilled fish oils (which are virtually devoid of metals or any other contaminants).
In conclusion, a single mouse study should not be grounds for discounting the already substantial body of human evidence indicating considerable benefit from using fish oil. The scientific evidence to date heavily favors the use of omega-3 products during chemotherapy in order to enhance life quality and boost treatment efficacy. Until much stronger evidence counters both my experience and the existing favorable data. I will continue to recommend fish oil to our patients. As always, I will suggest they use only those fish oils that have been molecularly distilled, while confirming that any and all supplements they take have undergone and passed independent testing.
