Thursday, August 25, 2011

How chemotherapy causes or contributes to the development of menopause?


Cancer and its treatment will undoubtedly cause many changes in your life.  One change you may experience from chemotherapy is the development of the symptoms of menopause.

How chemotherapy impacts the onset of menopausal symptoms is not fully understood, but it is clear that it can temporary or permanently impact on your menstrual cycle and cause the early menopause.

Chemotherapy causes premature menopause in about 30% of the women receiving treatment, particularly in those over 40. The symptoms of natural and premature menopause are the same, but they may be more severe when menopause is brought on prematurely. This is because in natural menopause the body adjusts to lower hormone levels over several years, while premature menopause causes a sudden and dramatic hormonal drop.

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Impact of chemotherapy on ovaries

  • A woman is born with a limited number of eggs in her ovaries. As she ages, this supply of eggs naturally diminishes. Some chemotherapy can damage or destroy eggs, reducing the supply. The effects of chemotherapy on reproduction vary with the woman’s age, the drugs used and the total dosages.
  • The frequency of early menopause after chemotherapy is difficult to determine, because there are many possible influences, and the rate varies with the age of the woman and the type of chemotherapy. Depending on the type of chemotherapy, the age of the woman and her number of eggs, the incidence of early menopause ranges from 0 to 100%. Rates of early menopause range from 21 to 71% in younger women, and 49 to 100% in older women.
  • There are many chemotherapy drugs that can affect reproductive function. A group of drugs called alkylating agents is the most likely to affect eggs and ovarian function. Cyclophosphamide, one of the most common drugs used in breast cancer treatment, is an alkylating agent. Taxol, also used in the treatment of breast cancer, may also affect ovarian function. The risk of menopause increases with age, most likely because older women have fewer eggs than younger women. For example, chemotherapy with cyclophosphamide, methotrexate and 5 fluorouracil (CMF – commonly used for the treatment of breast cancer) will usually result in loss of ovarian function in 33% of women under age 30, 50% of women aged 30-35, 75% of women aged 35-40 and 95% of women over age 40. Chemotherapy combined with radiotherapy affecting the ovaries is also associated with an increased risk compared to 

Chemotherapy influence on the onset of menopause

  • During chemotherapy, women may have irregular menstrual cycles or amenorrhea (disappearance of menstrual periods).  Some medications used in chemotherapy may also cause damage to the ovaries, resulting in menopausal symptoms or menopause.  
  • Menopause may be immediate or delayed, permanent or temporary when triggered by chemotherapy.  
  • There is no way to accurately determine how or when chemotherapy or other cancer treatments will affect your menstrual cycle. However, the chance that treatment will cause early menopause depends on a number of factors. These include:
    • Your age.
    • Your ovarian function before treatment.
    • The type and dose of chemotherapy you receive.
    • The dose of radiation you receive and the area of the body that is irradiated
  • Menopause is rarely a sudden response to chemotherapy.  When chemotherapy treatments begin, you may notice some menopausal symptoms, but usually the symptoms are delayed for several months after treatment is started.  This is natural. 
  • Menopausal symptoms may last for years after treatment is completed. 

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Menstrual flow after chemotherapy

Menstrual cycles vary from woman to woman.  Some women may experience less frequent cycles than they had prior to chemotherapy.  They may skip a period or increase the number of days between periods.  Other women may have more frequent periods.  Some women may not experience a change in the length of their menstrual cycles but the flow pattern may be different than it was before treatment (the number of days or amount of flow may diminish or the flow may be heavier).  Mixed patterns are also common: some women may have shorter menstrual cycles with heavier bleeding or infrequent cycles with many days of a very high flow. 

Even though periods tend to be irregular around the time of menopause, it is important to be aware of bleeding that is not normal for you.  It is very important to call your physician if you ever have very heavy bleeding that is associated with weakness or dizziness.

Periods return after chemotherapy

  • Many pre-menopausal women retain or recover ovarian function and their periods return after treatment is completed.  
  • Return of ovarian function may depend on the woman's age prior to treatment and the type of medication she received during treatment.

Recent Research

Giving the ovaries a rest when young women with breast cancer are undergoing chemotherapy may help prevent early menopause and preserve fertility. According to new research in the July 20, 2011 issue of the Journal of the American Medical Association, shutting down the ovaries by giving the hormone triptorelin when a patient is undergoing chemotherapy helped prevent early menopause.

Triptorelin appears to protect the ovaries by halting ovarian function temporarily, although it's not entirely clear why. The authors found that among women who took triptorelin in addition to chemotherapy, more than 63 percent regained the ability to menstruate, compared to about 50 percent of the women who had chemotherapy alone.

The study authors suggest that this option could help women with breast cancer who want to prevent early menopause. About 6 percent of women with breast cancer are diagnosed before age 40.



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