Thursday, February 5, 2015
Keep the Penile Cancer prevention argument out of the Neonatal Circumcision Debate
A commonly used argument to support the use of neonatal circumcision is the proven relative risk (not necessarily a significant absolute risk) benefit in preventing cancer of the penis. The purpose of this discussion is not to argue over the role of circumcision to prevent infections such as HIV (that's for another day) but to discuss why making an argument that it prevents penile cancer to justify recommending routine neonatal circumcision is a misuse of statistics.
Let's first set the context correctly. I am writing this from the perspective of residents of Westernized countries. Cancer of the penis in Westernized countries is very uncommon. The figures vary depending on which publication you look at and when the data was collected but using the very worst figures, the incidence is around 1-2 per 100,000 population.
Penile cancer is most commonly seen in men who are uncircumcised but there are often other factors additional to this. These include poor hygiene, poverty, smoking, human papilloma virus infection, sexual promiscuity, sex with animals and others. In my relatively limited experience of diagnosing and treating penile cancer, the majorities have been in uncircumcised men who were living in poverty and had poor hygiene. When we look at this list of risk factors, it is clear that many of these are much less of an issue in Westernized countries than developing countries. Before criticism is raised about sexual promiscuity and lack of condom protection still being a problem in Westernized countries, it pales into insignificance when compared to some developing countries.
Now let's compare the incidence of breast cancer. The incidence in Westernized countries is about 100-125 case per 100,000 population. Yes, this is a huge difference compared to penile cancer. Recommending circumcision to prevent penile cancer is like recommending bilateral mastectomy to prevent breast cancer. Okay, you might argue that bilateral mastectomy is a substantially more major operation that a circumcision? Fair enough. Why don’t we instead consider skin cancers involving the ear lobes which are not only far more common that penile cancers but to prophylactically remove the earlobes to prevent cancer in that location is not a major operation.
Another consideration is how many neonatal circumcisions would have to be performed to save one diagnosis of penile cancer? We do not have good data on this in the Western world because the incidence is so low. We cannot extrapolate data from developing countries where the incidence is relatively high. Without having the necessary data to make a number needed to treat analysis, we can make an intuitive assessment of this. Lets take the incidence in Israel which is about 0.1 cases per 100,000 where almost all are circumcised. Let’s take the incidence in Australia which is about 1 case per 100,000. It is obvious that the NNT is going to be massive. Imagine having to carry out 10’s of thousands of circumcisions just to save one diagnosis?
If zealots are using the argument that circumcision significantly reduces the risk of penile cancer to justify a stance of routine neonatal circumcision, they might as well support a far stronger argument for performing routine bilateral mastectomy to prevent breast cancer.
Remember that this blog piece is not an argument about whether circumcision can reduce the risk of penile cancer but the fanciful argument that this is why we can justify routine neonatal circumcision in Westernized countries. Keep the penile cancer argument out of the circumcision debate in Westernized countries.