In the earlier post, I demonstrated that the precancer time machine seemed to apply in the case of dcis and invasive breast cancer.
In today's post, I've used the latest SEER (The U.S. National Cancer Institute's Surveillance Epidemiology and End Results) cancer data to show that there seems to be the same phenomenon going on for melanoma precancers.
The topic of treating melanoma precancers has been somewhat controversial. It would seem to be a no-brainer that we can reduce the incidence of invasive melanomas by treating melanoma precancers (dysplastic nevi and in situ melanomas). Unfortunately, there is no epidemilogiic evidence to support this assertion. Basically, the incidence of invasive melanoma seems to be rising every year, despite our best efforts to stem the tide (through the use of sunscreens, avoiding exposure to strong sunlight, and treating precancers).
The latest SEER data (which covers cancer cases from 1973 to 2007) seems to offer some hope that conditions might be improving.
Here's the graph of invasive melanome incidence in the U.S. SEER population.
The tallest bars (blue) are the crude numbers of occurrences of invasive malignant melanoma. The middle bars (maroon) are the occurrences of invasive melanoma expressed as a proportion of the total number of SEER cases. The bottom bars (white), are the occurrences of melanoma expressed as a proprotion of the total population of the U.S. in the perspective years.
Here are the numbers:
crude of SEER of U.S. Pop
1973 001062 001916 000501
1974 001305 001938 000610
1975 001559 002116 000721
1976 001601 002116 000734
1977 001791 002337 000813
1978 001829 002347 000821
1979 001973 002460 000876
1980 002190 002645 000963
1981 002298 002690 001001
1982 002352 002714 001015
1983 002350 002617 001005
1984 002462 002638 001043
1985 002795 002864 001174
1986 002947 002942 001227
1987 003050 002879 001258
1988 002948 002743 001205
1989 003194 002896 001294
1990 003272 002816 001311
1991 003518 002853 001395
1992 003569 002786 001399
1993 003611 002860 001400
1994 003904 003097 001499
1995 004189 003283 001594
1996 004438 003641 001673
1997 004627 003668 001728
1998 004739 003663 001753
1999 004893 003704 001794
2000 005105 003832 001814
2001 005380 003911 001886
2002 005377 003857 001867
2003 005514 003993 001898
2004 005859 004062 001998
2005 006451 004431 002180
2006 006431 004335 002152
2007 006325 004172 002097
In the last two years studied (2006, 2007), the incidence of invasive malignant melanoma has dropped. Is this just a fluke, or does it indicate a real trend? There's no way to be sure, but inspection of the graph would indicate that it's the first time since 1973 when incidence has dropped two years running.
What about the corresponding incidence of in situ melanoma (the non-invasive precursor for invasive melanoma)?
Here's the graph for in situ melanoma.
Here are the numbers.
crude of SEER of U.S. Pop
1973 000035 000063 000016
1974 000059 000087 000027
1975 000081 000109 000037
1976 000096 000126 000044
1977 000155 000202 000070
1978 000177 000227 000079
1979 000177 000220 000078
1980 000263 000317 000115
1981 000276 000323 000120
1982 000326 000376 000140
1983 000384 000427 000164
1984 000466 000499 000197
1985 000638 000653 000268
1986 000723 000721 000301
1987 000782 000738 000322
1988 000824 000766 000337
1989 000976 000885 000395
1990 001127 000970 000451
1991 001192 000966 000472
1992 001373 001072 000538
1993 001375 001089 000533
1994 001599 001268 000614
1995 001920 001504 000730
1996 002091 001715 000788
1997 002258 001790 000843
1998 002533 001957 000937
1999 002765 002093 001013
2000 003202 002404 001137
2001 003508 002550 001230
2002 003656 002622 001269
2003 003429 002483 001180
2004 003604 002499 001229
2005 004060 002788 001372
2006 004048 002728 001354
2007 004291 002831 001422
The incidence of in situ melanoma keeps going up and up. That's as it should be. When we successfully cure more and more in situ melanomas, we reduce the incidence of invasive melanomas.
The lag between the rise in incidence of the in situ lesions and the drop in incidence of the invasive lesions is due to the precancer time machine phenomenon.
Can we be sure? Not yet. Hopefully, over the next five years or so, the data will become a little more convincing.
- © 2010 Jules Berman
key words: precancer, precancerous, skin cancer, dysplastic nevi, dysplastic nevus, dysplastic naevus, dysplastic naevi, cancer mortality, cancer prevention, carcinogenesis
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. If you like the book, please request your librarian to purchase a copy of this book for your library or reading room.
