October 8, 2007

Prostate Cancer: Survival Rates Vary According To Season

A current study on prostate cancer conducted by a team of American and Norwegian researchers revealed that the season of prostate cancer diagnosis is linked to the survival rate. Researchers analyzed the data of 46,205 Norwegian men who were diagnosed with prostate cancer from 1964 to 1992. They were divided into four different groups according to the seasons (image to the right). The overall findings suggested that men who were identified with having prostate cancer in the summer and fall have better survival than those who were diagnosed in the winter and spring. More specifically, those diagnosed in the winter and spring are 20 percent more likely to die within three years then those who are diagnosed in the summer and fall.

Each of the four seasons vary in their daily temperatures and weather patterns. The summer and autumn months, defined from June to November, have higher levels of calcidiol, an intermediate metabolite of vitamin D (see chemical structure to the bottom left), through ultraviolet exposure—a vitamin whose exposure is not as prevalent during the winter and spring seasons. The study, published in the journal, The Prostate, did not prove that vitamin D is the determining factor. However, study co-author Dr. Tomasz Beer, director of the prostate cancer program at the Oregon Health & Science University Cancer Institute, suggested that further research should be conducted on this possibility. Vitamin D has been shown to regulate cell differentiation and help sustain the immune system. Most importantly, this fat soluble vitamin is also known to slow down cancer growth. Alternate factors associated with vitamin D included age, food intake high in vitamin D, vacations in sunny southern areas, and the location of residency in Norway, were also examined to determine whether survivability was affected. Of all the variables examined, age is the risk factor that influences the chances of being diagnosed with prostate cancer because younger males readily produce more vitamin D than older males. As mentioned by the researchers “the capacity of skin to produce vitamin D when exposed to sunshine is about 40 percent lower in men 75 and older than in men 60 and younger” and therefore younger men had a slightly better rate of survival.

In this study, a relationship between the varying seasons and survival rates of prostate cancer has been proven to exist. Despite these findings, additional factors that could potentially affect the study include the type of treatments administered and the stage of the disease at the time of diagnosis. The older patients normally have a more advanced diagnosis of prostate cancer and are subjected to different treatments. This may have an overall effect on the survival rate. Furthermore, the skin color of these patients is another risk factor to consider in such a study. Dark-skinned people require more sun exposure to make vitamin D. This is due to the thickness of the skin layer called the stratum corneum, which alters the amount of absorbed ultraviolet radiation.

There are several factors to consider when conducting a study such as the one discussed in this post. The physical attributes, life style, environmental surroundings, and genetics are a few that need to be measured for a thorough research study. The discovery that certain seasons contribute to a better outcome in survival rates among men with prostate cancer seems promising for future treatments. However, since the study was conducted with Norwegian men, not all factors may be applicable to the general population of those who are diagnosed with prostate cancer. The importance of integrating vitamin D in our life style, especially prostate cancer patients, can help reduce the development of cancer. Researchers as early as 1936 were aware that skin cancer patients have reduced rates of other cancers when exposed to UV light even though excessive sun exposure may give rise to skin cancer. Prostate cancer patients and the general population need to be advised that moderation is the key in the intake of vitamin D and ultraviolet exposure as it is for other healthy lifestyle habits.

1 comment:

ABE said...

Thank you for your post. I found it to be very interesting, well written and definitely educational. My background in medical science is minimal, so I appreciated the precise yet “reader-friendly” approach you took in your writing style. Also, the links you included were extremely helpful in understanding both prostate cancer and the science behind vitamin D’s potential effects on its defeat. I would have also been interested to see some discussion of treatments currently in use. You mentioned in your post that “Researchers as early as 1936 were aware that skin cancer patients have reduced rates of other cancers”. I wonder whether any research has been done to study the effects of artificial sun on cancer, either as a preventative measure or as a treatment course. If so, that could be an interesting link to include. In terms of format, your graphics added both to the credibility of your post as well as giving non-scientific readers less of a sense of intimidation than many articles in this field I have come across. One thing that you might want to address, however, is the spacing in your first paragraph. I think perhaps the graphic had some effect when it was imported. Overall though, I thought this was a very well done post and I look forward to your insights into other topics in the future.

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