Friday, January 2, 2009

Cancers with two peaks in age distribution

To the casual observer, it doesn't make much difference whether a cancer has two peak in its age distribution or one peak. I'm devoting several blog posts to trying to convince readers that the distinction is very important, often implying that what we thought was one type of cancer is actually two different cancers, with similar morphology but with distinctive clinical features and different methods of treatment. Furthermore, several dozen of these cancers with two peaks in their age distribution, would not be discernible without a large cancer data set, such as the public use data files provided by the SEER (the U.S. National Cancer Institutes Surveillance, Epidemiology and End Results) project.

For this discussion, I've uploaded two pdf files

The first file is intended to be a resource for pathologists, epidemiologists and cancer researchers. It contains about 650 neoplasms, each with its age distribution. Details of the graphic represenations of the data are available in the file.

Most tumors have a simple, smooth age distribution, with a single peak. The graph of cancer rates (not occurrences), normalized against the age distribution of a standard U.S. population, often produces highest rates at the upper age range (because cancers in the elderly occur within a relatively small population of super-annuated individuals).

A typical cancer with one peak visible on a graph of occurrences (top) and of rates of occurrence normalized against a standard U.S. population (bottom). Click to see larger image.

Not all cancers have a single age-of-occurrence peak. Some have two or more peaks of occurrence.

I've provided a file that lists cancers with multimodal age distributions (i.e., more than one peak in the age distribution for the neoplasm):

There a about two dozen such cancers (out of about 650 listed in the seerdist.pdf file). Here are two sample pages from the bimode.pdf file:

Cancers with two peaks. Pairs of graphs are 1) occurrences by age and 2) normalized rates. Click to see larger image

By examining these two files and by correlating these observations with known features of the included cancers, we can draw important conclusions about neoplasms in general and the bimodal tumors, in particular.

Next blog on this topic.

-© 2009 Jules J. Berman
In June, 2014, my book, entitled Rare Diseases and Orphan Drugs: Keys to Understanding and Treating the Common Diseases was published by Elsevier. The book builds the argument that our best chance of curing the common diseases will come from studying and curing the rare diseases.

I urge you to read more about my book. There's a generous preview of the book at the Google Books site.

tags: common disease, orphan disease, orphan drugs, genetics of disease, disease genetics, rules of disease biology, rare disease, pathology, epidemiology, neoplasms