Lies, Damn Lies and Statistics


A national chain of restaurants used to issue discount vouchers on the back of supermarket receipts. Over time, they found they had more success offering ‘one free main meal’ than offering ‘15% off the total bill’, even though the total bill reduction usually amounted to a much larger saving for the customer. Their conclusion was that most people couldn’t easily calculate 15% of a potential bill, but they had no trouble understanding ‘free meal.’

If you like a bargain you’ve probably got a quick method for calculating percentages, and it’s made easier by retailers sticking to simple numbers. We know that 50% of something is half, 33% is roughly one third, 25% is a quarter and 10% is a tenth. Anything else and we look at the price, move the decimal point one place to the left to give us 10% and then double it for 20% or triple it for 30%. Or we just go with the notion that any discount is better than no discount and the higher the percentage the better the deal.

It turns out I was wrong, as I sat in my high school maths class and audibly rolled my eyes wondering how percentages were going to be the least bit useful to me in the real world. Percentages matter. Particularly when you get cancer.

Cancer involves a lot of difficult choices about treatment. Everything comes with side effects and risks. It’s easy to get terrified. If you can’t get your head around percentages that terror can be paralysing.

Some people take the ‘ignorance is bliss’ approach. They place themselves in the hands of their doctors and hope for the best. I have an enormous respect and admiration for the majority of people in the medical profession but I also recognise their human limitations. People make mistakes. They get tired. They can’t always keep up with all of the current research. If you think about the number of patients most of these people see in the course of a day, a week, a month, it gives you an appreciation of their wonderful memories and their obsessive note taking. I’m more of a ‘knowledge is power’ kind of person. I want to be actively involved in my treatment. To ask intelligent questions and to make informed choices. I know that ‘what happens next?’ and ‘can we book that in today?’ are both good questions.

But oh those statistics! Let’s see if I can hose them down.

The first thing you learn about triple negative breast cancer is this phrase: “A poorer prognosis than other types of breast cancer.” Pause for a crying break. Contemplate mortality. Settle down and find out what that actually means. It turns out that ‘poor prognosis’ means you’re looking at a 75% five year survival rate.

To start with, you get your head around the five year survival rate. Figures for cancer are expressed this way because your chances of having a relapse are much higher in the first five years. The longer you stay cancer-free, the better your prognosis. If you make it to 10 years without a relapse your life expectancy is about the same as anyone else. You can start worrying about heart attacks and strokes like the rest of the population! The point about the five year figures is that it helps to remember that these are your worst numbers, and they improve over time.

The other thing to remember about five and ten year figures is that a relapse isn’t a death sentence. A relapse means a new set of statistics that will, understandably, be more frightening than your original numbers, but there is still a survival rate.

75% means I have one chance in four of being dead inside five years. It also means I have three chances in four of being alive. That’s the raw statistic. Initially frightening but from my perspective, worth knowing. When I’m feeling a bit slack about looking after myself, ‘three chances in four’ is a serious motivator.

But I think we can immediately improve on 75%. In order to give you a five year survival rate, doctors need to use data from people that have already survived five years. Makes sense. What this means is that you’re looking at numbers from people that received treatment five or more years ago. All over the world, and in Australia in particular, there have been impressive improvements in cancer treatment in the last five years. It’s fair to expect that when triple negative patients get their statistics in five years time our survival rates will have been better. I think it’s conservative to say at least 5% better. That moves us up to 80% without even trying. Eight out of ten or four out of five. So already we’ve improved on the original statistic.

Remember whenever you hear medical statistics that they are always historical. In an environment where technology and medicine are advancing at a cracking pace that’s important information.

It’s possible to massage the 75% by adding in your own circumstances. This number reflects all cases of triple negative breast cancers. It doesn’t usually get detected early and, in many cases, people already have a tumour in another part of their body at the time of diagnosis. It’s very aggressive and spreads quickly. If you’re fortunate enough to have it contained to the breast, as I do, then your odds improve. The sooner you catch it the better. You can also figure into survival rates your general level of health, your lifestyle and the other things you do to improve your odds. The 75% figure includes people that were smokers, drinkers, over eaters and drug users. It includes people with underlying conditions that impacted upon their treatment and people that opted not to have any medical treatment, or chose alternative over mainstream. All of these are factors.

The strong message from these statistics is that everything I can do to support my treatment and improve my health will help to improve my odds.

One of the biggest changes to the treatment of triple negative breast cancer has been neo-adjuvant chemotherapy, which I’ve been having. It involves having chemotherapy first, before surgery. The advantages include immediately treating the whole body for any cancer cells. It turns out that we all have cancer cells wandering our body all the time. Even people that haven’t been diagnosed with cancer and never will be. Everyone. The reason those cells don’t develop into cancer is that our body recognises them as deformed and kills them. At some point a cancer cell manages to evolve in a way that turns off the flag that marks it as foreign, and our body gives it a blood supply to help it grow. A tumour is born.

Having something in your system that targets not only your tumours but any other highly aggressive, notoriously metastasising cancer cells is a good thing. If I’d had surgery I would have had to wait at least four weeks for chemotherapy and there’s a chance the cancer could have already laid down another tumour in that time.

It’s also reasonably common for triple negative patients to develop another tumour in their scar tissue if they have surgery first. There’s a view that because surgery disrupts the blood flow to the tumour site it may make it more difficult for chemotherapy drugs to target any remaining cancer cells. The other advantage of neo-adjuvant treatment is that doctors can see if the cancer responds to chemotherapy and whether or not the tumours are shrinking. Triple negative isn’t one cancer. It describes a group of cancers that share a common characteristic. Once the tumours are gone, chemotherapy becomes ‘best guess’. With neo-adjuvant treatment you can see the impact, and hopefully completely melt the tumours prior to surgery. Fingers crossed.

This treatment improves the odds of triple negative patients. Research from the UK is finding that around 40% of patients receiving this treatment achieve full pathological response. That means their tumours are dead and surgeons remove the surrounding tissue just to check. For these patients, their survival rates are the same as patients with other forms of breast cancer (currently close to 90%). Fingers and toes crossed.

I think it’s also important to view your statistics in the context of overall life expectancy. As a 51 year old Australian woman the average life expectancy is around 30 years. I know that some people find staring death in the face an odd way to stay positive but this number puts everything in context for me. I was never going to live forever.

Hopefully that’s given you a better understanding of how the survival rate statistics work, but the real quagmire comes when you start looking at the treatment statistics. Depending on who you ask, or what your read, mainstream cancer treatment is either leading edge medicine or brutal experimentation with lousy outcomes. It reminds me of being pregnant; you will hear horror stories. I find statistics very useful when sorting through this barrage of information, misinformation and conspiracy theory. First some basics:

Cancer is not one disease but a whole group of diseases that have some things in common. They all occur at a cellular level and they all involve a deformed cell attracting a blood supply so that it can grow and possibly spread. Statistics that apply to one kind of cancer do not apply to every kind of cancer.

Chemotherapy is not one kind of treatment but a broad description for a type of treatment that involves using drugs to target all of the cells in your body that reproduce quickly, including your healthy cells. Cancer cells reproduce quickly but don’t recover easily from chemotherapy. Healthy cells do. Statistics that apply to one type of chemotherapy to do not apply the every type of chemotherapy. Statistics that apply to the treatment of one type of cancer with chemotherapy do not apply to any other type of cancer. As a simple example, the aggressive nature of triple negative breast cancer means it responds better to chemotherapy than other, less aggressive forms of breast cancer.

Radiotherapy statistics are also complicated. This is an area of medicine that has benefited enormously from advances in computer sciences. What used to be a therapeutic ‘blunt object’ now uses three dimensional targeting and computer imaging. Statistics for radiotherapy need to be considered in this light.

Finally, there is not one kind of surgery and the skill of a surgeon is a major factor in these statistics. I think the best recommendation for a cancer surgeon is that they have a reputation for only needing to operate once. I’m not talking about relapse here, but people having to go back into surgery within weeks because it’s clear from the biopsy that something was left behind. I want a surgeon that’s going to get it right the first time. Not all do and this influences the overall statistics.

Your doctor has access to data bases that help to calculate the possible impact on your survival rate of various types of treatment. I like these numbers. All of these treatments have side effects and risks. In some cases those risks are life threatening. Without some data you can be left feeling as if you’re jumping out of the frying pan and into a volcano. So, keeping all of the above qualifiers in mind, here’s my numbers and what I get from them:

What happens if I do nothing? This is always my first question regarding any medical treatment. It turns out that for triple negative breast cancer the five year survival rate with no treatment at all is around 46%. That’s better than I thought it would be. A good way to think of anything close to 50% is that it’s a coin toss. For me, that’s not a great survival rate.

How does chemotherapy improve that? Based on the historical data, by 16%. That’s lower than I thought it was and hopefully that number will get much higher as the neo-adjuvant data kicks in, but even without that, 16% is a significant improvement. I think of it as a lottery with 100 tickets in it and first prize is my life. I’ve already got 46 tickets (survival rate if I do nothing). Would I like another 16 tickets? Before I make that decision I want to know what’s attached to those 16 tickets. One of them comes with a possible long term risk of leukaemia or heart trouble but when I look at my age and my overall life expectancy I’m still prepared to take that chance, given that all 16 tickets improve on my coin toss of a cancer. Chemotherapy isn’t for everyone. For some people the risks outweigh the benefits. Information helps you to be comfortable with whatever decision you make.

I apply the same kind of thinking to radiotherapy and the risks associated with that. The difficulty with assessing radiotherapy is that until I know how the chemotherapy and surgery went, I won’t have enough information to apply specific statistics. The more invasive the cancer, the stronger the argument for radiotherapy. At the moment I’m assuming best case scenario and even on those statistics it’s looking like a good idea. The other complicating factor with radiotherapy statistics is that some people’s odds have already been affected by chemotherapy and some haven’t and your age also affects your chances. Younger women have a higher chance of cancer coming back than older women. You can see why I call it a quagmire.

It’s useful to look at general figures for radiation. The chances of cancer coming back for a woman that has a lumpectomy without radiotherapy are 36%, but with radiotherapy that reduces to 17%. If the cancer had spread to lymph nodes then the chances of the cancer coming back rises to 44% and the chances are reduced by radiotherapy to 9%.

Like chemotherapy, radiotherapy includes some serious long term risks. There’s a 1% risk (one chance in 100) of getting another kind of cancer within 10 years. There’s also a risk of heart attack that peaks at around 25 years. I’ll run my lottery ticket analogy again. If I add radiotherapy into the mix I can now have around 90 of the tickets in a lottery of 100 tickets where the first prize is my life. One of those tickets might mean fighting another cancer battle and I’m okay with that. One of them might mean a heart attack at 75. I told the radiation oncologist that if I have a heart attack at 75 I’ll send him a thank you card! He’s promised me flowers in return.

I hope all of this helps people make informed decisions about treatment. My strong recommendation is to ask all of your treating doctors for data and take a pen with you to write it all down. Some of the information might seem terrifying but once you get your head around it there’s some positive stuff in there. Importantly, it helps you make decisions about your treatment that you’re at peace with. Perhaps the greatest hell for anyone with cancer is second guessing your choices. What if…..Should I have……..If only I’d known……….  When doubt sets in it really helps to know that you took the time to take everything into consideration; the general statistics, your personal statistics, your own attitude to risk and complications and your comfort level with any form of treatment.

I’ve opted for everything mainstream medicine can offer me, supported by complimentary treatments. Some people choose to have only some forms of treatment or none at all. I respect everyone’s right to make their own choices while encouraging them to do the research to ensure that those choices are informed. ‘Trust your instincts’ is lousy advice. My instincts have often led me down dark alleyways to be beaten up by circumstances that a little critical thinking could have avoided.

Finally, the statistics remind us that we are much more likely to survive breast cancer, even triple negative breast cancer, than to die from it. And that’s a really good thing to keep in mind.


7 thoughts on “Lies, Damn Lies and Statistics

  1. Excellent post. Thanks for letting the rest of us know how it feels to be on the receiving end of those confusing statistics. Congratulations for wading through them so thoroughly. Just like a seasoned investigator! FYC

  2. Megs, you had better survive all this,……….if I ever get cancer I want you there. I can see that I would be totally overwhelmed, I like the way you explain it all. Thank you so much for this information, it is so very interesting xox ❤

  3. This post has been so helpful for me. I’ve been agonizing over the decision to do radiation and mulling over the endless statistics. The choices are never clear cut. It’s a gamble either way.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s