It’s been a while since my last post. This past month has been a whirlwind time for me as I have had to write a thesis for my Masters end-of-year project not to mention being in a lab at least three days a week. As much as I’ve enjoyed it, I can’t help but feel I need to catch up with the world of cancer research. Therefore, I figured looking back at all of the major cancer stories this month would be pretty appropriate.

A Mixed Bag

So, what’s changed? Well, other than the usual dubious links between cancer and whatever the media deems as sensationalist enough to make the headlines, there’s been quite a lot occurring. Certain cancer incidence rates have seen a worrying increase for a start, so much so that the chance of a man developing cancer in their lifetime has risen to 1 in 2, as opposed to the 1 in 3 chance in women. Studies have shown a new technique in the delivery of drugs, using a biolistic particle delivery system (or “gene gun”) to fire a highly toxic anticancer drug directly into tumour tissues. Theories into the origins of cancer have arisen, with around 21 mutations – thought to account for the development of around 97% of cases involving the 30 most common cancers – being identified.

There are many more to look into but I fear there would be a serious overload of information. So here are a few of the more interesting stories to have emerged this month. Let’s start with the bad…

Case Study #1: Something Smells Fishy…

Let’s start with the most skeptical story to have hit the headlines in the past month: fish oil causes prostate cancer. The exposure of this story is just plain ridiculous when considering the basis of the study.

First to consider is that this was an observational study, meaning they examined data gathered from a previous experiment. So rather than producing results themselves, the people involved in this study were essentially looking for relationships within someone else’s dataset.

Secondly, the measurement of “fish oil supplements” did not actually involve any fish oil supplements. Let me clarify. The measurement made was of blood EPA and DHA levels, each of which are phospholipids found in fish oils. There were no “supplements” taken.

Thirdly, and probably most importantly, was the way in which the results were represented. Most media outlets highlighted one finding of the study: that high levels of EPA and DHA omega-3 fatty acids can increase the risk of high-grade prostate cancer by 71%, low-grade prostate cancers by 44% and all prostate cancers by a combined risk of 43%. Most failed to mention the finding that high levels of omega-6 fatty acids as well as trans fats were associated with a LOWER risk of prostate cancer.

So trans fats – which have been indicated across hundreds of studies to be associated with heart disease – can actually help you avoid prostate cancer? According to that logic, cutting fish out of your diet and adding plenty of cream cakes will protect you from developing the disease. Problem solved. Not only that but the “71% increase in high-grade prostate cancer” was related only to increased DHA levels – absolutely nothing to do with EPA. And these levels can be hugely influenced by a single meal containing fish anywhere in the 48 hours preceding a blood test (i.e. DHA levels can be very high for 48 hours following eating fish but then return to normal after this time period). Again, just something that was conveniently left out.

DHA and EPA can be found in fish oils whereas the third omega-3 fatty acid, ALA, can be found in flax seed oil

The reporting on this study has been shocking, even for the media’s standards. Most have chosen to ignore the fact that no fish oil supplements were actually taken in the study and haven’t even distinguished the type of omega-3 fatty acid that is supposedly linked to an increased cancer risk. The experimenters haven’t helped themselves either with the fact that there is no indication of controlling various dependents such as diet, age, ethnic origin or family history – all of which will affect the findings.

The intentions of the headlines were to instill fear over fish oil supplements and, unfortunately, they will have. If it has scared you at all into not taking your supplements, just take this into consideration as a final thought: if fish oil caused an increase in prostate cancer, then surely a population with a diet heavily based on fish and seafood e.g. Japan would indicate just that?

Well Japan has one of the lowest prostate cancer incidences in the world. MUCH lower than the US and Europe.

Case Study #2: More Booze = More Breast Cancer…?

Fast forward to this morning and I find myself reading an article about an apparent correlation between alcohol consumption during the time period between a women’s first menstrual cycle (menarche) and their first pregnancy and breast cancer risk. Needless to say, I thought Mr.Omega-3 Reporter had come back to frustrate me again.

This research looked at members of the Nurses Health Study II involving 90,005 registered nurses with no cancer history. The elaborate method of measuring alcohol uptake during 4 age periods was somewhat confusing but their method of data collection was much clearer: questionnaires were sent to members of the study every two years to fill out their alcohol intake per month or per week in predetermined units of measurement. The results suggested that women who drank more alcohol during the time between menarche and first pregnancy correlated with an increase of breast cancer. Also found was a relationship between the length of time between menarche and first pregnancy and breast cancer, with risk increasing with time.

Now maybe it’s just me but I would find it pretty hard to recall the amount of alcohol I had drunk each week or month within the past TWO YEARS. I wouldn’t be able to tell you how much alcohol I drank in the past month alone. How the data collected for this study was believed to be reliable is beyond me. It’s clear to anyone that as time goes on, our memories either fade out or they can become exaggerated. The reliability of the questionnaire answers therefore is terrible at best.

Something to Look Into?

There is however an interesting point to this study. I was intrigued when it mentioned that time between menache and pregnancy correlated with breast cancer. It’s pretty much common knowledge that hormones affect our chances of cancer, especially oestrogen’s effect on breast cancer. So much so that hormone receptor over-expression is tested in breast cancer tissue as a diagnostic and prognostic marker. It has also been shown that breast tissue is particularly susceptible to carcinogenic damage during adolescence in females due to the hormone-controlled proliferation of cells. The study itself mentions that alcohol consumption between menarche and first pregnancy correlated with more oestrogen and progesterone positive (ER+/PR+) tumours than ER-/PR- tumours.

Oestrogen-positive tumour cells can be treated using Tamoxifen which essentially prevents any oncological behaviour. Does elevated oestrogen correlate with a longer time between menarche and breast cancer instead?

Perhaps then, alcohol does play some part in affecting hormone levels and in turn susceptibility to increased hormone signalling, resulting in abnormal tissue growth. But then it could be that alcohol has nothing to do with it and its down to hormones alone. Alcohol is a damaging agent, so the study is more excusable than the fish oil-prostate cancer drivel. Unfortunately though, as mentioned before, the method of data collection is so unreliable that nothing produced from this study can be taken seriously. 

Moving Forward

I can only hope that articles like these cease finding their way into mainstream media but unfortunately that’s about as unrealistic as the media ceasing to exist altogether. Articles referring to studies like these damage public perception of science through confusion and scare-mongering. The number of comments I read related to these articles that consisted of such things as “why do we fund this kind of research?” and “soon everything will be linked to cancer” was concerning. They create a sense of deception in studies which was not at all intended from the researchers. Even though the methods used have been pretty poor in each instance, it’s the media’s misrepresentation of facts and manipulation into sensationalist stories that are worse. When analysed, each study has a point which is unfortunately overshadowed by poor reporting. Especially when studies are taken out of context as definitive evidence for a cause of cancer. No wonder nobody trusts the media.

Read more:

The fish oil study: http://jnci.oxfordjournals.org/content/early/2013/07/09/jnci.djt174.abstract

The alcohol/breast cancer study:

http://jnci.oxfordjournals.org/content/early/2013/08/24/jnci.djt213.full.pdf+html

Advertisements