Latest report from National Cancer Registry confirms predicted increase in cancer numbers

The number of new cancers diagnosed in Ireland continues to increase year on year, the most recent report from the National Cancer Registry, covering the years 1994 to 2005, shows. The overall increase was just under 3% per year during this period. However, we calculate that most of this increase is due to our ageing and growing population. When we allow for these factors the risk to an individual of developing cancer is increasing very little. The picture is even more positive for cancer deaths; these have remained more or less the same since 1994, and the risk of dying of cancer is falling by 1.5 % per year.

Despite these overall trends, the risk of developing some cancers continues to increase. These cancers include, for men, cancer of the prostate (7% annual increase in risk), kidney (4%), melanoma (4%) and lymphoma (2%) and, for women, cancers of the kidney (4%), uterus (2%), breast (2%) and lung (2%). The risk of dying from most cancers is falling, but for melanoma of the skin, cancer of the kidney (in men) and cancer of the rectum the risks are increasing.

There is no single explanation for these trends. Of concern is the continuing upward trend in lung cancer in women, which is due to smoking. Equally worrying are the trends in melanoma of the skin, which is related to sun exposure. It is striking that a number of these cancers (those of the kidney, breast and uterus) have all been linked to overweight and obesity, which are rapidly increasing in Ireland. This gives concern for the future, if the trends in weight gain continue.

The rapid increase in prostate cancer is almost certainly due to many small and slow-growing cancers being picked up by the PSA blood test, which is being increasingly used; most of these cancers would not have affected the man during his lifetime and would have gone undiagnosed had he not had the blood test. Given that the death rate from prostate cancer is falling, it is very unlikely that there is any real increase in the underlying risk of this cancer.

Cancer risk seems to be, in general, quite evenly spread throughout the country. The report confirms earlier impressions of higher risk for many cancers in Dublin, and to, a lesser extent, in Cork. However, none of the geographical differences observed were major. The Registry is working on a more detailed analysis of the relationship between area of residence and cancer risk, which we hope to publish later this year.

As might be expected from the fall in death rates and improving survival from cancer in Ireland (see our press release of August 24th), there were clear changes in cancer treatment over the past 12 years. The proportion of patients having chemotherapy and radiotherapy increased for almost all cancers; overall, between the period 1995-1998 and 1999-2003 there was a 27% increase in those having chemotherapy and a 24% increase in radiotherapy. These increases were most notable for cancers of the stomach, oesophagus and pancreas and seem to signal a more active and positive approach to the treatment of these cancers, which have a relatively poor outlook.