One of the most often asked question to me is whether the incidence of cancer has increased in last 100 years. Is cancer a disease of 21st century? Is it the price we pay for pollution, toxins, plastic, radiation etc.
Cancer statistics can indicate that incidence of some cancer has increased and for some has decreased. My view on the subject is slightly different. I personally believe that "Observational bias", if that is the right term, always misinforms us.
You may hear many elders or even middle age people mentioning that diseases have increased and that they are seeing more number of people with cancer nowadays.
Some of my views:
1.Cancer has been there since time immemorial. It is mentioned from the time of 1500-1600 BC and also by Hippocrates (460–370 B.C).
2. The average life expectancy has steadily increased in the last century. Cancer being predominantly a disease of old age you have potential more number of people at risk as well as suffering from cancer.
3. Please note, if we use the numerator denominator concept, the incidence might not have really changed much. Let me explain, the population was less, less people used to live beyond 60 and therefore you had less number of people having cancer.
4. Our diagnostic modalities have significantly improved. This picks up more cancers. Previously we did not even know, who suffered, when they suffered and how they died.
5. We are also picking up cancers which would not have manifested at all! Example prostate cancer.
6. More number of people are seen in the society living with cancer or having been cured of it.
So the way i look at this is, we are living long enough to be afflicted by cancer. But this optimism is of no help unless we find ways and means to evade it, eliminate it. What is the progress we have made against cancer?
Has survival improved in the last 30 years?
Has mortality rate declined?
We will look at these questions in next few posts.
The same is true for some neurological conditions like Parkinson, Alzheimer's. They are at the other spectrum. Old age risks us to degenerative disease or a disease like cancer. A fine balance between these two kinds of diseases is "life".
References:
1. History of Cancer
2. New Yorker, Cancer World
3. Cancer Statistics
4. Inverse relationship between cancer and Alzheimer's:
a. http://www.bmj.com/content/344/bmj.e1442
b. http://roma.cshl.edu/pdfs/Sebat%20et%20al%20Science%202004.pdf
c. http://www.captura.uchile.cl/bitstream/handle/2250/10598/BEHRENS_Inverse_Association.pdf?sequence=1
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