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“A critical weekly review of important new research findings for health-conscious readers”

BREAST CANCER, PHYSICAL THERAPY &

LYMPHEDEMA

Arm lymphedema, or chronic swelling of the arm, occurs in 10 to 30 percent of women following treatment for breast cancer.  When the lymphatic drainage network in the arm and hand has been disrupted by the surgical removal of axillary (armpit) lymph nodes, or by radiation therapy to the axilla (or, sometimes, following both types of treatment), the delicate network of lymphatic vessels that return excess tissue fluid back to the heart can become obstructed. This lymphatic obstruction can then result in chronic swelling of the hand and arm.  Patients with significant lymphedema of the arm following breast cancer treatment may experience considerable swelling (edema), heaviness, stiffness and discomfort of the affected hand and arm.

Unfortunately, there are no known effective methods available to prevent lymphedema, and once significant lymphedema does develop, compression sleeves and soft tissue massage are the primary treatment modalities currently available.  Unfortunately, currently available lymphedema treatments are often not highly effective for many patients, and there is no known cure for lymphedema once it develops.

Now, a newly published research study, in the British Medical Journal, suggests that physical therapy, when initiated early after breast cancer surgery, can significantly decrease the risk of arm and hand lymphedema.  In this prospective randomized clinical research study, 120 women who underwent removal of their axillary lymph nodes for breast cancer were randomized to one of two groups.  Women assigned to the experimental group underwent physical therapy 3 times per week, for a total of 3 weeks.  Physical therapy techniques used in this group included manual lymph drainage and soft tissue massage techniques, as well as progressive shoulder exercises.  Both groups of women also underwent the same lymphedema management educational course, but the control group of women did not receive any physical therapy interventions.

Among the 116 women who completed at least one year of follow-up, 18 women (16 percent) went on to develop lymphedema.  Fourteen of the women who developed lymphedema were in the control group, while the remaining 4 women were in the experimental group.  Thus, in this clinical study, early physical therapy following axillary lymph node dissection (ALND) was associated with a very significant 72 percent reduction in the risk of developing lymphedema, at least within the first year following breast cancer surgery.

Whether or not the use of early postoperative physical therapy can reduce the incidence of arm lymphedema over periods longer than one year is unknown at this time, and additional follow-up of the patients who participated in this clinical research study will be required to answer this very important question.  However, this is one of the very few studies available that suggests a role for physical therapy in the actual prevention of arm and hand lymphedema following ALND for breast cancer.  If additional, mature follow-up of these patients confirms a long-term benefit from early postoperative physical therapy in preventing arm lymphedema, then a strong case could be made for the routine use of early physical therapy in women who undergo ALND, and perhaps, as well, women who undergo sentinel lymph node biopsy with subsequent radiation therapy to the breast and armpit (axilla) area.

For additional information and resources related to cancer-associated lymphedema, please click on the links below:

http://www.cancersupportivecare.com/Abstracts/asbdpbtps.html

http://meeting.ascopubs.org/cgi/content/abstract/23/16_suppl/8185

http://www.annalssurgicaloncology.org/cgi/content/abstract/15/7/1996

http://www.cancerlynx.com/sln.html

http://doctorwascher.com/Archives/11-23-08.htm

http://doctorwascher.com/Archives/8-16-09.htm

For a somewhat lighter perspective on Dr. Wascher, please click on the following YouTube link: 

http://www.youtube.com/watch?v=7-Tdv7XW0qg

Welcome to Weekly Health Update

“A critical weekly review of important new research findings for health-conscious readers”

SOY ISOFLAVONES REDUCE BREAST CANCER

RECURRENCE RISK

Regular readers of this column are already aware of the controversy surrounding soy isoflavone intake and breast cancer risk.  As happens frequently in clinical research (unfortunately), contradictory research findings have made it difficult to understand the true relationship between dietary soy intake and breast cancer risk (if one exists).  There is, for example, both laboratory and clinical data suggesting that a diet rich in soybean-derived products may be associated with a lower risk of developing breast cancer.  At the same time, because genistein and other dietary isoflavones are known to weakly mimic the effects of estrogen, there has been some concern that a diet rich in isoflavone “phytoestrogens” may increase both the risk of developing a new breast cancer and the risk of developing a recurrence of a previous breast cancer.  (In fact, there is data from laboratory research studies showing that genistein can indeed fuel the growth of human breast cancer cells growing in culture dishes, when exposed to high concentrations of this soy-derived isoflavone.)

A growing body of public health research, primarily from Asian countries where tofu and other soy-based foods are frequently consumed, appears to link increased soy consumption with a decreased lifetime breast cancer risk, particularly when soy-based foods are consumed during adolescence, during the time when development of the female breast is most active (Soy & Breast Cancer Risk).  (Interestingly, there is also recent research suggesting that soy products might also reduce the risk of prostate cancer, which is another hormonally driven cancer:   Genistein & Prostate Cancer Cells, Dietary Soy & Prostate Cancer Risk.)

Although epidemiological research is, increasingly, suggesting that a diet rich in soybean-derived foods might lower a woman’s lifetime risk of developing breast cancer, many breast cancer experts have remained apprehensive regarding dietary isoflavone intake in women with a prior history of breast cancer, in view of the estrogen-like effects of these “phytoestrogens.”  As I have already noted, there is considerable research data available to suggest that soy-derived isoflavones can, at least under certain laboratory conditions, stimulate estrogen-sensitive breast cancer cells to grow and divide.  These research findings have left many oncologists feeling uncomfortable in recommending soy-based foods to their breast cancer patients.  Now, a newly publish public health study in the Journal of the American Medical Association suggests that soy-based foods may actually reduce the risk of breast cancer recurrence, and death due to any cause, in women who have previously been diagnosed with this very common form of cancer.

In this study, which was performed in Shanghai, China, 5,042 female breast cancer survivors (ages 20 to 75 years) were followed for an average of almost 4 years.  All of these patient volunteers underwent detailed surveys regarding their lifestyle habits, including their diets.  These patients, who were originally diagnosed with breast cancer between 2002 and 2006, were surveyed at 6, 18, 36 and 60 months following their original diagnosis with breast cancer.  

The results of this study indicate that the breast cancer survivors who consumed the greatest amount of soy-based foods in their daily diets were 32 percent less likely to experience a recurrence of their breast cancer when compared to the women who consumed the least amount of soy-based isoflavones.  Moreover, the women who consumed the greatest amount of soy were also 29 percent less likely to die, from any cause, when compared to the women who consumed the least amount of soy-derived foods.

A particularly interesting and unexpected finding of this study was that both women with estrogen sensitive breast cancers and women with tumors that were not sensitive to estrogen appeared to experience a significantly decreased risk of breast cancer recurrence if they frequently consumed soy products.  Another important finding of this study was that women who were taking the estrogen-blocking cancer treatment drug tamoxifen also appeared to enjoy a reduced risk of breast cancer recurrence with higher levels of dietary soy intake.  Additionally, the researchers noted that high levels of soy intake appeared to be about as effective in reducing the risk of breast cancer recurrence as the breast cancer prevention drug tamoxifen, alone.

The results of this very important study mirror the findings of the only other prospective clinical study that has looked at the impact of soy-based foods on breast cancer recurrence (the “Life After Cancer Epidemiology,” or “LACE,” study).  The LACE study, which was performed in the United States, followed nearly 2,000 breast cancer survivors for, on average, more than 6 years.  In the LACE study, women who were taking tamoxifen, and who also consumed the highest amount of soy-based dietary isoflavones, were 50 percent less likely to develop a recurrence of their breast cancer when compared to women who reported the lowest consumption of soy-derived foods.

As I have pointed out previously, epidemiological research studies based upon dietary surveys are susceptible to several types of bias which, in turn, can cause researchers to draw the wrong conclusions.  In this case, however, there are now two large prospective cohort studies that have reached essentially the same conclusions (albeit with a rather limited duration of patient follow-up).  Both studies strongly suggest that high levels of soy-based isoflavones in the diet may be able to significantly reduce the risk of breast cancer recurrence.  Based upon the findings of this large Chinese study, the apparent cancer risk reduction effect associated with high levels of soy intake also appears to benefit premenopausal and postmenopausal women, as well as women who are taking the estrogen-blocking drug tamoxifen, women with estrogen-sensitive tumors, and women with (counter-intuitively) estrogen-resistant tumors.

In view of the limited duration of patient follow-up in both of these clinical breast cancer studies, as well as the limitations of survey-based epidemiological research in general, I would like to see updated data from both of these studies after at least 10 years of patient observation before I would be willing to tell my breast cancer patients that they should significantly increase their dietary soy intake.  On the other hand, the rather compelling data presented by both of these clinical research studies will also make me less anxious when any of my breast cancer patients decide, of their own accord, to increase their intake of soy-derived isoflavones.

Note:  Weekly Health Update is currently undergoing an extensive upgrade to better serve its tens of thousands of health-conscious readers around the world.  Beginning in January 2010, newly archived columns will be available by selecting the “Archives” tab on the right side of your screen (all archived columns prior to January 2010 will continue to be available by selecting the “Archives 2007-2009” tab at the top of the screen.)

Disclaimer: As always, my advice to readers is to seek the advice of your physician before making any significant changes in medications, diet, or level of physical activity