New Cancer Statistics Released
The NHS Information Services Division have released new statistics on cancer incidence in Scotland. Incidence means the number of new cases of cancer diagnosed over a specific time (in this case 1985 to 2006).
The statistics are always a couple of years behind, simply because it takes a long time to gather all that information and analyse it. In the past when I’ve quoted figures from ISD Scotland they’ve been from 2004, now they’ll be from 2006!
Why is the timescale important? Why 1985 to 2006? While some cancers are common (e.g. breast, lung and colon cancer) other cancers are rarer. If you only have a few cases (e.g. under a hundred a year) then you will see a big change in the numbers from year to year. Such a change is usually due to chance, we’re not machines and cancer can strike at random. So scientists compare data over a longer time period (e.g. 10 years) so that we can see if cancer levels are increasing or decreasing.
Cancer Research UK have a good summary of the statistics on their website, you can find it in the April News section. Some types of cancer are decreasing. That means less people are being diagnosed with stomach cancer, cervical cancer, ovarian cancer (in women) and pancreatic cancer (in men).
The levels of lung cancer in men are falling (by 23 % in the last 10 years) but the levels of lung cancer in woman are increasing (by 5 % in the past 10 years). This reflects “historical smoking trends” which means that 20-30 years ago increasing numbers of women were taking up smoking. In Scotland today 26 % of men and 24 % of women smoke (about 1 million people). In Scotland, in 1972, 53 % of men smoked and 43 % of women smoked. For more detailed information on Smoking in Scotland visit the Scottish Public Health Office report from February 2008 on “Tobacco Smoking in Scotland” or for a shorter version read this ASH factsheet.
What about other cancers? The levels of breast and prostate cancers appear to have risen (i.e. more people are getting diagnosed with breast and prostate cancer). There are probably many reasons for this, but most importantly we are much better at looking for these cancers now than we were 20 years ago. The more you look for these things, the more you find them. Many more men are given the PSA screening test for prostate cancer and many more women are having mammograms. Woman up to age 70 are included in screening now. However, some women may be developing breast cancer because they are delaying having children (the earlier you have children the lower your rate of breast cancer) or because more women are drinking alcohol than in previous generations.
Rates of colorectal cancer (bowel cancer) have fallen by 10 % over the past 10 years, this could be due to improvements in diet and exercise but more research is needed to see if this is true.
Scotland has some of the best health service data in the world (being a small country helps, Iceland and the Scandinavian countries have pretty good data too.) We have been collecting cancer data since 1958. What good does it do? Well, unless you can measure something it is very hard to change it. We would all like the number of cases of cancer to drop, but to do this we need to know the scale of the problem (and how it changes over time) and that’s why these sort of statistics are important.