RADIATION TREATMENT OF PROSTATE CANCER & RISK OF SECOND CANCERS
Exposure to high doses of ionizing radiation, whether from a nuclear explosion or from radiation therapy for cancer, has long been known to increase the risk of cancer formation. A growing body of clinical data is helping to further develop our understanding of secondary radiation-induced cancers.
current understanding about radiation-induced cancer is based upon
observation of the Japanese survivors of the World War II atomic
catastrophic failure of the
More recently, several studies have reported upon the incidence of secondary cancers in adults who were treated with radiation therapy for lymphoma during childhood and adolescence. An increased incidence of cancers of the lung and the female breast has been confirmed among patients who previously underwent extended-field chest irradiation (also known as mantle radiation therapy) for Hodgkin’s Lymphoma, and these secondary cancers typically occur 15 to 20 years following treatment. Rare cancers of the bone and cartilage, called sarcomas, have also been associated with prior radiation therapy treatments. Now, a new research study suggests that certain forms of prostate cancer radiation therapy may also be linked to an increased risk of subsequent radiation-induced secondary cancers.
Currently, there are several different treatment approaches available for prostate cancer therapy. Surgery can be performed to completely remove the prostate gland (prostatectomy) when the tumor is still confined to the prostate. Implants of radioactive seeds, placed within the prostate gland (brachytherapy), can also be used to destroy cancer within the prostate. External beam irradiation is another form of radiation therapy, but unlike brachytherapy, external beam irradiation is delivered by a machine that concentrates radiation onto the prostate gland from a source external to the body. Although great progress has been made in fine-tuning the delivery of radiation to the prostate gland with both brachytherapy and external beam irradiation, there is, inevitably, some “collateral damage” that occurs to the organs and tissues that surround the prostate, as it is impossible to confine 100 percent of the delivered radiation dose to the prostate gland alone.
new study, in
the Journal of Urology, evaluated
cancer treatment records of more than 240,000 men who had previously
treated for prostate cancer with prostatectomy, brachytherapy, external
radiotherapy or a combination of brachytherapy and external beam
between 1988 and 2003. The
data for this
study was collected from the massive Surveillance, Epidemiology and End
(SEER) national cancer database, which is maintained by the National
study was conducted by
In this study, the authors compared the incidence of subsequent cases of cancers of the bladder and rectum occurring in these 243,082 men. The men who underwent prostatectomy alone, and who did not receive any radiation therapy, essentially served as the “control group” for this study.
An almost insignificant increase in the risk of bladder cancer was seen in the men who underwent brachytherapy alone. However, there was a more pronounced and statistically significant increase in the risk of both bladder cancer and rectal cancer observed among the men who received either external beam radiotherapy alone or combined brachytherapy and external beam radiotherapy. Compared to the men who underwent prostatectomy alone, external beam irradiation was associated with an 88 percent increase in the relative risk of developing bladder cancer, and a 26 percent increase in the relative risk of developing rectal cancer. Among those men who received both brachytherapy and external beam radiotherapy, the relative risk of developing bladder cancer was 85 percent higher than what was observed in the men who underwent prostatectomy alone, while the relative risk of developing rectal cancer was 21 percent higher. (It should be noted that “relative risk” is a measure of the difference in risk between two patient treatment populations, and is not the same as the “absolute risk” of developing a particular disease.)
In this retrospective study, which involves a relatively short duration of clinical follow-up, external beam irradiation for prostate cancer (either administered alone or in combination with brachytherapy) was associated with a significant increase in the risk of developing subsequent cancers of the bladder and rectum.
Since most studies of radiation-induced secondary cancers have shown an average biological lag time of 15 to 20 years between radiation therapy and the diagnosis of secondary malignancies, the findings of this study may actually underestimate the long-term risks of secondary bladder and rectal cancers in men who have previously received external beam radiotherapy as treatment for their prostate cancers. At the same time, however, recent and continuing improvements in the accuracy of radiation therapy delivery have significantly reduced the “innocent bystander” effect, whereby clinically significant doses of radiation are absorbed by the organs that surround the prostate gland (namely, the bladder and the rectum). As a final note, all retrospective studies that are based upon prospectively collected data, such as this study, are subject to potential biases, including the “completeness” of the clinical data that is present within large databases such as the SEER database. However, based upon a large body of clinical literature on this topic, the findings of this particular study are not at all surprising, or unexpected.
All patients who are planning to undergo therapy for prostate cancer should first talk with their oncologists about the unique risks and benefits associated with each potential treatment option before choosing the best and most appropriate form of therapy.
SEXUAL CONTENT ON TV & TEEN PREGNANCY RISK
Although the effects of violent and sexual content on television, or on video games, on adolescents and young adults is the subject of considerable debate, there are multiple recent studies that appear to substantiate the concerns of many parents who wrestle with these issues. For example, several clinical research studies have recently found that children who frequently play video games with violent themes are more likely to engage in aggressive or antisocial behavior at school and at home.
In view of the enormous impact of teen pregnancy on individuals, families and society, many parents and family advocates have viewed with alarm the increasingly unfiltered sexual content present in both movies and television shows. A new Rand Corporation study, just published in the journal Pediatrics, has concluded that there may well be a significant link between exposure to television shows with sexual content or themes, on the one hand, and the likelihood of pregnancy prior to age 20. This study was funded by the National Institute of Child Health and Human Development, which is part of the National Institute of Health (NIH).
In this study, data from prospective surveys of teens were analyzed over a 3-year period. A total of 1,762 adolescents between the ages of 12 and 17 anonymously completed surveys regarding their sexual experiences and their television viewing habits, and the same group of teens then completed the same survey one year later. The incidence of teen pregnancy in this group of adolescents was monitored for a period of 3 years.
Sexual content in television shows measured by the surveys included: (1) sexually-oriented behaviors such as kissing, intimate touching, and implied or depicted intercourse; and (2) discussions about sexual plans or desires, or about sexual behavior that had already occurred, or “expert advice” about sexually-related topics.
The results of this study demonstrated a linear association between heavy exposure to sexual content on television and the initiation of intercourse and other sexual behaviors during adolescence. The teens who anonymously admitted to watching the greatest number of sexually-themed television shows were 2 times as likely to initiate sexual intercourse within the following year as were the teens who watched the least amount of sexual content on TV. In terms of age-related sexual behavior, 12 year-olds who watched the greatest number of television shows with sexual themes engaged in sexual activities at a level comparable to 14- and 15-year-old teens who watched the least number of shows with sexual content. An especially interesting finding of this study was that television shows that featured only discussions about sexual activities were still associated with an increased likelihood of engaging in intercourse, and in teenage pregnancies, among adolescents viewing such shows.
Other adolescent behaviors linked with the early initiation of intercourse included: older age, hanging out with older friends, achieving lower grades at school, sensation-seeking behaviors, and rule-breaking behaviors (e.g., skipping classes).
On the other hand, behaviors most associated with a lower likelihood of intercourse during adolescence included: having parents who monitored their teens’ behavior, having more educated parents, having parents who disapproved of teenage sexual activity, and living with both parents (please note that the greatest deterrents to adolescents engaging in intercourse, based upon the results of this prospective clinical study, involved parent-related factors…).
In this study, an early age at initiation of sexual activity (including intercourse), and the incidence of teen pregnancy, were found to strongly correlate with the extent to which television shows with sexual content (including mere discussions about sexual activities and behaviors) were viewed by teens. Conversely, minimizing viewing exposures to such television programming, and being supervised by two parents who disapproved of adolescent sexual behavior, was associated with the lowest rates of teen sexual activity and teen pregnancy.
Many parents will respond to the findings of this research study with something along the lines of, “No, duh….” However, this is the first prospectively conducted research study to confirm what many of us parents have long believed. My advice is to stay connected with your teens, and stay involved with their lives, even when they demand that you do otherwise.
Dr. Wascher is an oncologic surgeon, professor of surgery, a widely published author, and the Director of the Division of Surgical Oncology at Newark Beth Israel Medical Center
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Copyright 2008. Robert A. Wascher, MD, FACS. All rights reserved.
Dr. Wascher's Archives:
10-26-2008: Smoking & Quality of Life
10-19-2008: Agent Orange & Prostate Cancer
10-12-2008: Pomegranate Juice & Prostate Cancer
9-21-2008: Does TylenolŪ (Acetaminophen) Cause Asthma?
4-27-2008: Stents vs. Bypass Surgery for Coronary Artery Disease; The “DASH” Hypertension Diet & Cardiovascular Disease Prevention; Testosterone Therapy for Women with Decreased Sexual Desire & Function
4-6-2008: Human Papilloma Virus (HPV), Pap Smear Results & Cervical Cancer; Human Papilloma Virus (HPV) Infection & Oral Cancer; Hormone Replacement Therapy (HRT) & the Risk of Gastroesophageal Reflux Disorder (GERD)
12-16-2007: Honey vs. Dextromethorphan vs. No Treatment for Kids with Night-Time Cough, Acupuncture & Hot Flashes in Women with Breast Cancer, Physical Activity & the Risk of Death, Mediterranean Diet & Mortality