Understanding risk, evidence, research, statistics

Understanding risk, evidence, research, statistics

Understanding risk, evidence, research, statistics On the forums we often have very interesting threads about risk, causes of breast cancer, prognosis, statistics, research etc.

Yet most of us, unless we happen to be scientists, biologists, or mathematicians lack crucial knowledge and understanding about things like how to read statistics, how to evaluate the methodology or findings of research, how to weigh up ‘risk’ and apply it to our individual circumstances. Hence the speculation we all love to indulge in about whether this or that treatment is more effective than another; what a 10% increase in this or that means; what to ‘believe;’ when the press sensationalises tentative research findings. I’ve tried to find out about these issues and its been a steep learning curve, and there’s still much more I’d like to know.

But who in the breast cancer charity world can help? At the Westminster fly-in I attended a couple of good workshops, one on research, one on risk factors…but this was at a campaigning conference. I’d like to see such issues incorporated into the Living with Cancer days BCC runs. I’ve not been on one of these days nor a Healthy Living Day because I don’t fancy most of the programme: am I the only woman with breast cancer who doesn’t want to sit around doing hand aromatherapy, or visualising my tumour, or getting some hands on healing (I’ll laugh and that would upset other people; Not that I don’t occasionally like a good massage) ; talking about my self esteem (its fine thanks though is always good to talk with other women about their experiences) and learning how to put on make-up (I rarely wear any…though I’d like the freebie creams I’ve heard about).

I think if we are to be really ‘empowered’ people living with cancer we need to be able to talk to our doctors as knowledgeable adults, not dependent children; we need to have the confidence that our opinions are backed up by evidence, and to understand the nature of evidence so we can contest competing vesions of ‘truth.’ We need to have the confidence to challenge the myths and misconceptions about breast cancer and the charlatans who exploit people with cancer. Knowlege also add to that sense of control which we all know helps the process of living with uncertainty.

What’s anyone else think?


I agree I think we need to push the cancer charities into providing such training for people who would like it, though I feel pretty empowered anyway and never like a dependent child, but it would be useful to have some more structured formal knowledge about such things.

This is a really difficult area Hi Jane,

I have actually studied loads of statistics and was even a teaching assistant for a statistics class once (although a slightly different type of statistics are used). It was some of the hardest money I have ever earned, although that was somewhat down to the lecturer, who treated anyone who was struggling as if they were an idiot.

In the US, the National Breast Cancer Coalition’s Project Lead provides training for breast cancer patients who want to get their heads around the trials.

Until then, here is something I wrote for the her2support website to help other patients understand all of the trial results. You might find it helpful.

I guess my one caveat is that it is also important to keep in mind certain aspects of trial design, such as did all the women in the control group receive what is now a standard chemo treatment? The rapid introduction of new chemos and other treatments makes this an increasingly common problem. Was the trial set up to examine certain issues: for example, in HERA it looks like women who received anthracyclines alone got more benefit that those who received anthracyclines and taxanes, but the patients were not randomly assigned those treatments, so its impossible to compare them.

Hazard ratio: The lower the figure the better. For HERA the hazard ratio was .54 (54%), meaning that for every one hundred women who would have recurred without herceptin, only an estimated 54 of the recurred when herceptin was given after treatment. The risk reduction is 1 - the hazard ratio (1-.54) which is the same as 100%-54% =46%.

The 95% confidence interval. You will note that I said ‘estimate’ above, because there is always some uncertainty in statistics, so it’s not clear whether the value is exactly 54%. For the HERA results, the 95% confidence interval was .43-.67. This means that it is 95% certain that of one hundred women who would have recurred without herceptin, only between 43 and 67 of them recurred when herceptin was given. So they are 95% certain that the risk reduction is somewhere between 33% (100%-67%) and 57% (100%-43%).

The P-value is the probability that something is purely a coincidence. If the p-value is .01 that means that there is a 1 in a hundred chance that it is a coincidence. If it is .05, there is a 5 in a hundred chance of it being a coincidence. In general, only p-values under .05 or sometimes .01 are considered statistically significant. The smaller the number the better. To demonstrate statistical significance, it is important to have a large number of cases, which brings me to HERA.

The HERA results show that the p-value for disease free survival is less than .0001. This means that the chance of this being a coincidence is less than 1 in 10,000. However, the p-value for overall survival is just .26 which means that the chance of this being a coincidence is 26%. Therefore, it has not shown a statistically significant improvement in overall survival yet. However, HERA was not as far along as the other studies, so it may simply be too early to see a difference in overall survival, since the followup was only one year following women entering the trial. I would caution that HERA included about 1/3 node-negative women, some of whom received really old chemo drugs believed to be less effective against HER2, such as CMF, so it cannot be compared directly with the herceptin-based chemo studies.

The combined studies on herceptin-based chemo seem to have used a two-tailed test, which I am much less familiar with, but again the same rule about p-values values under .05 or 5 in 100 being good news is the same. For distant disease free survival, there is only a 1 chance in 10,000,000,000 that this is a coincidence (I think, I’ve never seen a p-value this small!). For overall survival, herceptin-based chemo again achieved statistical significance (.015) with there being just a 1.5 chance in 100 of this being a fluke.

Hope this is helpful.

Take care,


— hI jANE — wHEN I read your thread I couldn’t have agreed more. I keep saying that knowledge is power and it is only when we are given facts that we know to be true can we then feel we have some control over our bodies and the treatments ‘offered’ to us.

I would love to back you in this because I become so confused when I am given conflicting advice, even on simple little things, like we have a thread where coffee protects against cancer, and switch on tv this week to see coffee causes cancer.

However, I am a simple being with probably below average intelligence and as the thread progressed I realised that to help would be beyond me. The maths threw me completely and I did not understand some of the points being made. Sorry.

If there IS anything I can do to help, I would be happy to do so, but fear that I am not the only one who thinks all that is happening is over their heads and am afraid of making a fool of myself. (Hence your point of not having confidence to argue/discuss when at hospital appointments). What you suggest is VERY important but I don’t see what simple minds can do to help. If you can give me something then please do and it shall be done.

Joy xxx

I do so agree I am a lawyer, married to a mathematician with an interest in Probability Theory, so am in a hugely better positon than most to be able to conduct research and assess evidence. Nevertheless, I sometimes struggle with statistical concepts. Only 2 days ago I was alarmed (OK, I asked, so only have myself to blame) when I learned that the risk of a new primary cancer in my remaining breast would be 1-in-4. This stunned me, even though on the way home from the hospital my husband told me this means it is unlikely to happen or, more properly, that risk for something “unlikely to happen” is defined as 1-in-4. This hauled me down from my internal screaming heights only just a little bit!

I am also left cold by the programmes for the Healthy Living days (I have never worn make-up and simply can’t see the point of it: my attitude has always been that men don’t paint their faces so why should I?) So, yes, something a bit meatier would be appreciated by a good number of BC patients. I am a worrier by nature, but have always felt that knowledge is power. I think that lectures on, for instance, advances in research and treatment of BC would be well received.

Part of the problem is reporting I think that part of the problem is the sloppy way that things are reported, even twisted, by journalists. There are so many times that reporters misconstrue research or make it say things that the medical researchers never actually said that I can see why people get confused. I suppose the reporters are trying to be helpful, but they often do more harm than good. Perhaps it’s the health reporters who need the training.

I agree too I’m all for gaining knowledge and raising awareness, and think it would be great if some of the myths and uncertainties could be cleared up. If not only for us who are directly affected by cancer, but for those who aren’t. After all, they too could be affected in the future.

However, athough I have looked into and probed for information about my own position I personally don’t feel the need to know everything, and sometimes feel a bit like ignorance is bliss. I have never enquired about my prognosis, because quite frankly I don’t want to know at the moment. Not to say that this might change.

As for the Healthy Living days, I’m going on one next month. I don’t wear make up, and I have never been one for beauty treatments etc but as I have been off work for a long time I thought it would be a pleasant day out for a change that doesn’t involve hospitals. It will also be nice to meet others in the same boat as me.

I’m not sure if I’ve really added anything worthwhile here, but just wanted to add my view.


Reporters Having spent a bit of time over the last weeks ranting to reporters (local and national) - I couldn’t agree more that here is an area where increased knowledge of disease/diagnosis/prognosis and all that this entails is needed - One one occasion, I was asked by someone who started the conversation by saying they didn’t know much about the herceptin I was getting but “was it working?”. I tried to explain but I doubt it went in - individual was also surprised by the statement form me that I’d never be given the all clear from BC.

Its been said before on these forums - the “press” only want the stories we all hate “BC was the best thing that ever happened to me” etc. etc.

It will be interesting to see how the BBC cover the subject in the edition of Panorama which I am told is planned for 29th January.

Media I agree with Christine, I think a significant amount of blame can be laid at the door of the media. I have to say that the majority of the articles I’ve read seem to oscillate between giving an unnaturally rosy picture of treatment and survival rates or depressing cases. Statistics just aren’t sexy enough to sell newspapers.

I also think that a problem for the media is the number of different types of breast cancers that are diagnosed. It is difficult to make a general report because there seem to be so many variables. Whenever I read about new advances in drug treatment, I immediately think of Jane: er- and pr-. And why should it be that bc is one of the few cancers that is never really cured, only in remission?

Some people don’t like to know the statistics or survival rates, some want to know everything. I tend towards the former and strongly believe that these details should be available and accessible to those who want to know.

A good, thought-provoking debate.


Research Funding I would like to understand much more about how research into breast cancer is funded - where does the money come from, who decides how it should be spent and how do the various organisations that spend the money provide value for money and ensure they don’t duplicate work carried out by similar organisations.

On this forum, we’ve touched on the subject of why Government doesn’t push research into lifestyle and diet, and I would also like to add in environment as well. For example, ChristineMH recently drew our attention to the 63 studies in the past 30 years which indicated a link between Vitamin D deficiency and breast cancer incidence and yet the “official” response seemed to be that we need more research. What a disservice to breast cancer patients that after 63 studies and 30 years that’s the best they can say on the subject of Vit D.

Who decides what areas of research are funded? Where does the funding come from?How much say do the providers of funds have in what’s researched and does this create a research culture where the best interests of the patients are number 1 priority or is this clouded by the financial interests of the fund providers (pharmaceuticals aren’t going to fund research into Vit D) and the researchers?

If you go into the Charities Commission Website, you can find the Financial Accounts for registered charities. I looked at Breakthrough and Cancer Research UK as I wanted to see who their corporate fundraisers were and how much funding they provided. Breakthrough’s main ones are M&S and Avon. Avon fund a number of research posts. I could not find who CRUK’s Corporate Sponsors were, yet I think that information should be publicly available.

Research Although I am of the Henry Ford school of statistics and damned lies! I am very interested and still really do not have a clear idea of rates of recurrence either specifically or generally. I did not really understand that part of the onc’s information. In fact my husband and I (oh ideas, above my station again), both left that meeting hoping the other had grasped that particular bit of information. Far too embarassed by that stage to go back and own up.

Has anyone heard of the new Cancer charity ‘Abreast’ which is patient focussed and patient involved. Could this be the way forward? As for healthy living days - dunno - I’ve been virtually isolated since diagnosis, would hate it if it were too girly girly - not like that at all.


Good questions I too, have often wonder whether research is coordinated, both within the UK and internationally, and how this is done. I know that in some R&D intensitive industries, the competing! companies get together to map out where the technology is headed and work on the basisof this ‘road map.’ I wonder if the same is done with breast cancer or cancer in generally. At least now the big US clinical trials database www.clinicaltrials.gov seems to include alot of info about non-US trials. I know that one of the things that the oncologists do when they go to those big US conferences is to coordinate trials, but I don’t know about research.

The big area where things don’t get done is non-lucrative research. The good news on vitamin D is that the US government seems to be funding research into whether vitamin D might prevent high-risk patients from developing bowel cancer, the cancer for which the vitamin D link is strongest, so somebody is looking into vitamin D, albeit not for breast cancer. They are also funding research on Vitamin D for breast cancer, but only to prevent bone loss. Still, there’s always the hope that those studies might give a hint about any possible effect on breast cancer survival.

It’s just a bit frustrating because I think that vitamin D is likely to be a problem for the UK and therefore is an obvious area for research (like Australia and melanoma or Tunisia and Inflammatory Breast Cancer). My sister received a prescription for vitamin D when she lived up in Glasgow, but only because most of her GP’s patients were Asian and had a high rate of vitamin D deficiency due to their dark skins and modest clothing. The GP tended to test all her patients, even whites with fair skin like my sister.

I think, too, there is a big problem in getting the non-lucrative research into practice. One U.S. trial indicated that node-negative, ER- patients could reduce the risk of their cancer coming back by 42% over five years by greatly reducing their fat (the difference for ER+ patients was not significant). Now the trial left some questions unanswered, such as whether the ER- patients mainly did well because they lost more weight or whether the type of fat mattered (the US diet is very high in omega-6, which may be problematic for some types of breast cancers), but it seems like something pretty harmless. Yet, I have only heard of one oncologist bringing this up with a patient, even though might be very useful research.

Looking at that low fat diet Hi Christine

I think the way you have reported teh 42% reducation in cancer recurring for er- tumours highlights the probelms with statistics and percentages.

A quick look at 42% and you think gosh that’s a lot. But go to the actual research and you find that it is based on 478 women with er- tumours (I think with no node involvement but not sure). Of the 478, 205 were on a low fat diet with a daily avergae fat intake of 33.3 grams. The rest were on a regular diet with daily fat intake averaging 51.3 grams.

Of the 205 28 women 13.7% had a recurrence, compared to 59 women 21.6% on the regular diet. Yes this is statistically significant but all we can conclude is that a low fat diet may reduce the risk of recurrence for some people.


But isn’t that always the case? It is true that the low fat diet didn’t do anything for a sizeable number of women, but that is true of conventional treatments as well, as we both know all too well. After all, herceptin received an incredible amount of attention at the same conference for reducing recurrence by 46%, which still means that it failed to work for alot of her2+++ women. The whole ‘cure’ business was hype. And, of course, there aren’t alot of options for many ER-, node-negative women if it comes back. Some things are worth a shot, I think.

I don’t think that CRUK has corporate sponsors. Its corporate involvement comes more from spinoffs from its research (such as through Kudos, which was recently sold to AstraZeneca). It seems to use venture capitalists to separate the research side from the commercialization side, which I think is good.

great topic brilliant and so true. i feel like i’ve had to become an oncology and stats specialist in only four months! and so difficult when my onc is quoting the HERA trial at me, and I’m quoting the BMJ and NMEJ re taxanes and chemothepathy. had a really bad week last week when i just thought, he’s the expert, I should go with him, but then went back to the research and worked out that I am right! so now i just feel unsupported by an overworked onc! (not sure which is worse).
thanks to Christine for those explanations on the stats - really helpful.

— This erudite discussion is beyond me so I am bringing it down to my level! The trouble with statistics is that they are just that - figures - and they do not necessarily apply to you, good or bad, that is the issue.

Statistically I should not have got BC:

I did not menstruate early
did not have my children late
did some breast-feeding
never smoked
never been over-weight
always been fit & eaten well
no family history of BC
been a veggie since late 20’s (age that is not 1920s!)
couldn’t afford to drink wine etc until mid 30s
went nearly 10 years but re-occurred
only 1:4 have HER2 but I have
liver mets survival stats are 8 -12 weeks (I am still here 3 years later)

Need I go on?

I am really useless at maths but I wonder what the statistical odds of me getting BC cancer? I wonder if the odds were the same as me winning the lottery? If so why did I get BC and not loads of money?


I Agree Hi Blondie

I am much the same as you and so was really surprised to get BC, I Breast fed 3 children, my last for 18 months! and have always been skinny and a healthy eater and feel sometimes that no matter what you do some things will happen, even so I’m still stuffing myself with blueberries and drinking pomegranet juice just incase it helps.

Stats My surgeon told me the chances of me getting BC at my age were 1% - and here I am

Statistics are about populations, not individuals All that statistics can give you is a probability. They can’t tell what will happen to any individual, just what is likely.

Unless you have one of the known genes, the probability of any individual getting breast cancer is alot less than 50%. However, the probability of any individual winning the lottery jackpot is really tiny, but somebody wins almost every week.

Alot of the well-known risk factors don’t even apply to the less common types, like the triple negative or her2 positive subtypes, making things more complicated. For example, childbearing does not seem to have any relation to her2.

I think statistics are useful mainly for knowing whether treatments are as good as they look.