� � Feb-10-2010
A recent study has warned women who have been recommended to take tamoxifen to avoid relapse of breast cancer to keep away from the anti-depressant medication Paxil and all other generic versions of the medicine owing to the perilous interactions the drug may have with other substances. Scientists have said that Paxil, generically called paroxetine, have shown to counteract with tamoxifen resulting in a higher fatality risks owing to breast cancer.
It may be mentioned here that generally physicians recommend tamoxifen to treat as well as prevent breast cancers that are positive estrogen receptors. This drug acts by obstructing the results of the hormone.
According to Dr. David Juurlink, the co-author of the research paper printed in the edition of the British Medical Journal, tamoxifen is a very well known means for chemotherapy. Providing further details regarding the drug, the scientist, who is associated with the Institute for Clinical Evaluation Sciences (ICES) in Toronto, said that it passes on incredible advantages for survival, while paroxetine just denies the patients of these benefits. The patients are deprived of the benefits of tamoxifen, as paroxetine gets in the way of the body generally deals with tamoxifen.
During the course of the research, scientists at the Institute for Clinical Evaluation Sciences examined the health and treatment records of as many as 2,430 women in Ontario in the age group of 66 and 75 years. All these women had been prescribed tamoxifen during the period between 1993 and 2005 to avoid the relapse of breast cancer. In addition to tamoxifen, all these women were also using anti-depressant medicines called selective serotonin re-uptake inhibitors (SSRIs), such as widely accepted medications - Paxil (paroxetine), Prozac (fluoxetine) and Zoloft (sertraline). In fact, it is common to prescribe SSRIs for women taking tamoxifen as it is said to help in alleviating the usual side effects of tamoxifen - conditions like anxiety, depression and hot flashes. The study found that more than 25 per cent of the women taking paroxetine had a damaging consequence vis-�-vis the survival of the patients and these were apparently not common in the case of the other SSRIs.
Dr. David Juurlink has stated that during the research they observed that when tamoxifen was used in combination with paroxetine, it enhanced the hazards of death owing to breast cancer. He further said that using the two drugs concurrently increased the fatality risks in a manner that matched up to some extent of overlapping. The findings of the research determined that the longer paroxetine was used concurrently with tamoxifen, the greater was the risk of fatality owing to breast cancer. He clarified that on an average the patients had 41 per cent overlapping. In other words, the patients were taking tamoxifen as well as paroxetine concurrently around 41 per cent of the time.
According to a rough estimate prepared by the researchers, when women took both the drugs concurrently for 41 per cent of the time, it meant that there would be one additional death due to relapse of breast cancer among each of 20 women undergoing treatment every five years. What is horrifying is the estimation that the risks of fatality due to recurring breast cancer increased to one in every seven women if tamoxifen was used in combination with paroxetine for all the time or 100 per cent of the time during the treatment regimen. According to Dr. Juurlink, there is a strong case for recommending a change in the anti-depressant medication, if women are taking tamoxifen in combination with paroxetine.
At the same time, the scientist from the Institute for Clinical Evaluation Sciences in Toronto advised women not to stop taking tamoxifen. He also suggested that any woman taking paroxetine in combination with tamoxifen should not abruptly stop taking the anti-depressant medication, as it may result to other troubles, including a withdrawal syndrome. Hence, in such cases it is advisable that women taking both the medications should talk to their physician before they stop taking paroxetine.
Dr. Juurlink further mentioned that although they did not come across any association between taking Prozac and Wellbutrin (bupropion) and increased risk of death among women undergoing treatment to prevent recurrence of breast cancer, it is best that they also avoid these two drugs too. According to him, both Prozac and Wellbutrin are also known to get in the way of the metabolism of tamoxifen and somewhat negate its effect.
Appreciating the work done by the scientists at the Institute for Clinical Evaluation Sciences in Toronto, the director of the Toronto-based Familial Breast Cancer Research Unit of the Women's College Hospital, Dr. Steven Narod said that the findings of the study published in the British Medical Journal were not only an excellent research paper, but also of considerable importance vis-�-vis the therapy for women to avoid recurrence of breast cancer. While Dr. Narod, who was not associated with the research in any manner whatsoever, acknowledged that the research paper was not any kind of evidence regarding the consequences of using tamoxifen and paroxetine concurrently, but said that it does provide enough suggestions. Giving his opinion on the subject, Dr. Narod said that he did not believe that using tamoxifen in combination with paroxetine augmented the risks of death in women taking both the drugs, but agreed that paroxetine did negate the advantages of tamoxifen. Paroxetine is neither unsafe nor noxious, but indirectly increases the fatality risk among women being treated to prevent breast cancer relapse.
Nevertheless, Dr. Steven Narod is concerned that the common people are likely to dangerously get the wrong idea about the usage of tamoxifen and arrive at the conclusion that taking the medication may not be good for their health. Emphasizing that tamoxifen is a highly useful medication. Actually, the medication is especially effective in women who are enduring estrogen receptor-positive cancer, as it decreases the hazards of relapse of breast cancer by almost 50 per cent.
On the other hand, Dr. Karen Gelmon, an expert in the study of cancer (oncologist), appeared to be very guarded while evaluating the research paper. Actually, findings of different previous researches on the subject are different. Dr. Gelmon points out that while a number of earlier studies on this topic point out that using a number of SSRIs, such as Prozac and Paxil, are likely to get in the way of the body's capability to absorb tamoxifen, some other researches undertaken on the subject say that there is no relation whatsoever between taking tamoxifen in combination with the anti-depressants and the rate of fatality among women undergoing treatment to prevent recurrence of breast cancer. Hence, Dr. Gelmon opines that the end result of the researches is quite fascinating, but they do not clarify or establish anything. She asserts that the findings of the recent research on the topic by the scientists from the Institute for Clinical Evaluation Sciences in Toronto cannot be accepted as the 'gospel truth', since more studies are necessary to establish the truth in this progressing field.
Dr. Karen Gelmon further said that since the manner in which the research was conducted, evaluating something called 'retrospective information' obtained from previous prescriptions of women undergoing treatment for prevention of breast cancer relapse, it is very much possible that there could be other substances or occurrences that get in the way of the body's capability to metabolize tamoxifen that the scientists are yet to ascertain.
Substantiating her view, Dr. Gelmon said that the research undertaken by the scientists at the Institute for Clinical Evaluation Sciences in Toronto does not make any mention of whether the women, who were subjects of the study, dutifully followed their course of treatment with tamoxifen. She said that it has been seen that around 40 per cent of women usually do not follow their treatment routine. Nevertheless, Dr. Gelmon had the same opinion as Dr. Steven Narod that physicians treating women to avoid recurrence of breast cancer and taking tamoxifen and need an anti-depressant should try and prescribe other anti-depressant medications like Effexor (venlafaxine) or Celexa (citalopram), as they are not found to negate the benefits of anti-cancer medications.