|Vol. 23, No. 18||October 1, 2001|
Two Recent Breast Cancer Studies Reveal Increased Cancer Rates
The results from two recently published studies on breast cancer show two different factors that may actually worsen the disease.
The first study, released in the publication Chest, the journal of the American College of Chest Physicians, links smoking to the spread of breast cancer. The second study, published in the Journal of the National Cancer Institute, shows a surprising downside to the popular drug tamoxifen.
Breast Cancer Patients Warned Against Smoking
In the first study, researchers reviewed the hospital records of more than 80 women diagnosed with primary breast cancer and secondary breast cancer that had spread to the lungs. The hospital records were then compared to other cancer patients, similar in age and background, but whose breast cancer had not spread to other areas of the body. The researchers found that the breast cancer patients who smoked were nearly twice as likely as nonsmokers to have the disease spread to their lungs.
Although smokers do not have a higher incidence of breast cancer, medical experts do know that there is a higher breast cancer death rate among those who smoke. Past research has also shown that despite treatment for breast cancer, it is common for a relapse to occur with secondary tumors typically forming in the lung, bone, liver, and brain.
The study's authors conclude that smoking weakens the lung making it especially susceptible to malignant cancer cells. Past research has shown that smoking triggers a number of health hazards to the lung including altering the lung's immune function and causing lung injury.
However, the researchers add that other behaviors, common among smokers, may also play a role in the spread of breast cancer to the lung. Past research has shown that smokers are less likely to follow a healthy diet and are less physically active than nonsmokers.
In addition, the study also discovered that the women whose cancer had spread to the lungs were far less likely to undergo hormonal therapy in comparison to the women whose breast cancer had not spread. Hormonal therapy involves the use of anti-estrogen drugs, known to be effective in treating breast cancer.
The researchers are unsure of why the patients who smoked did not receive the hormonal treatment. They say it is possible that the patient refused treatment, or it was not recommended, since it is known that tamoxifen along with smoking increases the risk of blood clots.
The scientists conclude that more research is necessary to determine if cigarette smoking also plays a role in the spread of other cancers, and if smoking cessation at the time of the cancer diagnosis has an impact on the patient's health.
Tamoxifen May Stimulate the Growth of Another Deadly Type of Breast Cancer
The anti-estrogen drug, tamoxifen may have a surprising downside in its role against breast cancer. A recent study shows the drug may actually increase the risk of developing a new type of breast cancer, which is more difficult to treat and is more deadly.
Tamoxifen has been found to be effective in treating breast cancer by interfering with the female hormone, estrogen. Earlier research has shown that estrogen triggers the growth of a certain type of breast cancer tumor. These breast cancer tumors are known as estrogen receptors, or ER-positive tumors. Tamoxifen blocks the estrogen so the tumor is not able to grow. The drug also helps prevent any new ER-positive tumors from developing.
A number of clinical trials show that tamoxifen improves the 10-year survival rate of women with breast cancer and also reduces the risk of the cancer's recurrence. However, despite the drug's effectiveness, it is known that many ER-positive breast tumors do not respond to tamoxifen and many eventually develop a resistance. The study's authors believe that the resistance is due to the drug causing a different kind of breast cancer to develop, one that is not sensitive to estrogen.
The researchers reviewed the medical history of almost 9,000 breast cancer patients. Approximately half of the patients took tamoxifen in addition to undergoing surgery, or radiation, or both. The other half did not take tamoxifen.
They found that after eight years, the patients who took the drug had a 10 percent reduced risk of developing cancer in the other breast. However, the researchers also found an increased risk of the more aggressive estrogen-negative cancer tumors. In fact, the tamoxifen users were almost five times more likely to develop the estrogen-negative cancer tumors than the non-tamoxifen users.
The researchers say this is an extremely important finding that supports the urgent need for further breast cancer drug studies. Currently, there are no drugs that specifically target estrogen-negative tumors. They add that tamoxifen is still a powerful drug effective in the treatment of ER-positive tumors and that this recent finding should not change the clinical practice of tamoxifen use.
The American Cancer Society strongly agrees. The health organization states that women taking tamoxifen should continue since the medication's benefits far outweigh the risks. The Society adds, most importantly, the study shows the need for more research to find drugs effective in treating tumors resistant to tamoxifen.
- Courtesy of The Methodist Health
Care System's online column "Healthy Knowledge"
©2006 Texas Medical Center