Perimenopause and menopause
Iatrogenic menopause
Menopause after cancer treatment
In many women, menopause does not come naturally but as a result of cancer treatment. Chemotherapy can stop the ovaries from working. Surgical removal of the ovaries causes an immediate menopause. Radiotherapy to the pelvis causes permanent damage to the ovaries. In breast cancer, ovarian suppression with GnRH analogues, aromatase inhibitors and tamoxifen cause or worsen the symptoms. This menopause often comes suddenly and at a young age. The symptoms are therefore usually stronger than in a natural menopause and seriously affect quality of life. Even so, they are often not treated well enough, because attention rightly stays on the cancer.
Does every woman enter the menopause?
Surgical removal of both ovaries causes an immediate and permanent menopause. After chemotherapy, however, the picture is different. Periods often stop during treatment, but in many women they come back after some months. Amenorrhea after chemotherapy therefore does not always mean menopause. Whether the ovaries start working again depends mainly on age, on the medicines and their dose, and on the ovarian reserve before treatment. Radiotherapy to the pelvis causes permanent damage to the ovaries, depending on the dose.
In a 2020 study of 107 premenopausal women who had chemotherapy for breast cancer, periods stopped in 54% of women under 40 and in 82% of women aged 40 or older. Among the women under 40, periods came back in 12 of 13. Among the women aged 40 or older, they came back in only 29%. GnRH analogues during chemotherapy protect the ovaries. In a meta-analysis of five randomized trials with 873 women, premature ovarian insufficiency fell from 31% to 14%, and there were almost twice as many pregnancies.
Why does it matter whether a woman without periods is really in menopause? There are two reasons. The first is pregnancy: the ovaries can start working again, and the woman can ovulate and become pregnant even without periods. She therefore needs contraception, and after breast cancer contraception without hormones, for example a copper coil. The second is cancer treatment: aromatase inhibitors protect only when the ovaries no longer make estrogen. If the ovaries start working again, an aromatase inhibitor alone is not enough. For this reason, the oncologist confirms the menopause with repeated measurements of estradiol and FSH and does not rely only on the absence of periods. When the ovaries stop for good before the age of 40, the condition is called premature ovarian insufficiency. More in the article Premature ovarian insufficiency.
After chemotherapy: periods stop and come back
Periods stopped
Periods came back, among those whose periods stopped
Premature ovarian insufficiency after chemotherapy
What applies after breast cancer?
In women with a history of breast cancer, the guidelines do not recommend systemic hormone replacement therapy. In the randomized HABITS trial with 442 women, a new breast cancer event occurred in 39 of 221 women on hormone replacement therapy and in 17 of 221 women without it. The risk was about 2.4 times higher. In the LIBERATE trial, tibolone also increased recurrences, by about 40%. The practice's approach after breast cancer is clear: no systemic hormone replacement therapy. The data in detail, including the gray zones, are described in the article Menopausal hormone replacement therapy. Not taking hormone replacement therapy does not mean that a woman has to put up with the symptoms. For every symptom there is now an evidence-based non-hormonal treatment.
Which symptoms weigh most heavily?
Hot flashes are the best-known symptom. In daily life, however, three other problems often weigh more heavily on the woman: poor sleep, sexual problems and depression. These problems often go untreated, because the woman does not mention them and nobody asks. The practice focuses on them.
What about sleep?
In a study of 300 women after breast cancer, 19% had insomnia that met the criteria of the disorder. In 58% of them, the cancer had caused or worsened the insomnia. Night sweats and hot flashes, fear of recurrence, pain and some medicines interrupt sleep. Insomnia in turn affects mood, concentration and tiredness.
The first treatment is cognitive behavioral therapy for insomnia (CBT-I). In a randomized study in women after breast cancer, CBT-I improved sleep, and the effect lasted for one year. The doctor treats night-time hot flashes at the same time, because they are often the reason for waking up. Sleeping pills help only for a short time.
What helps the vagina, the bladder and sexual life?
In a meta-analysis of 19 studies with 2,684 women with breast cancer, 73% had sexual dysfunction. The cause is not only vaginal dryness. Lower desire, body image after breast surgery, tiredness, depression and the relationship with the partner play an equal role. The American Society of Clinical Oncology (ASCO) recommends that the doctor asks every woman about her sexual health and offers treatment, counseling or couples therapy when needed.
Vaginal dryness, pain during sex and urinary infections are especially common, mainly with aromatase inhibitors. The first choice is non-hormonal moisturizers and lubricants. When these are not enough, low-dose local estrogen is an option. Its use is considered safe, but close cooperation with the oncologist is very important. In a study of 49,237 women from Scotland and Wales (JAMA Oncology, 2024), the use of local estrogen did not increase deaths from breast cancer. In a Danish study of 8,461 women (Journal of the National Cancer Institute, 2022), local estrogen did not increase recurrences overall. In women taking aromatase inhibitors, however, the risk of recurrence was about 39% higher, with no increase in deaths. For this reason, the decision is different for each woman. Pelvic floor physiotherapy and, after radiotherapy, vaginal dilators also help.
Treatments without hormones after breast cancer
What about mood and depression?
In a meta-analysis of 72 studies from 30 countries, 32% of women with breast cancer had depression. The sudden fall in estrogen, poor sleep, hot flashes, fear of recurrence and changes in the body act together. Depression is not a normal reaction that the woman must put up with. ASCO recommends regular checks for anxiety and depression in all people after cancer, and psychotherapy or medication depending on severity. Venlafaxine and escitalopram also help with hot flashes. In women taking tamoxifen, the doctor avoids paroxetine and fluoxetine.
Why do weight and metabolism matter?
After an iatrogenic menopause, the risk of weight gain is higher. In a study of women with breast cancer, the start of menopause and chemotherapy were independent factors for weight gain in the first year, and women who had chemotherapy gained 2.5 kg on average. The risk of metabolic syndrome is also higher: belly fat, high blood pressure, high blood sugar and abnormal blood lipids.
These changes worsen the outlook of breast cancer in the future. In a meta-analysis of 12 studies with 23,832 women, weight gain of 10% or more after diagnosis was linked to 23% higher overall mortality. In a 2025 meta-analysis with 42,135 women, metabolic syndrome was linked to a 1.69 times higher risk of recurrence and a 1.83 times higher risk of death from breast cancer. This is why checks of weight, blood pressure, blood sugar and blood lipids are part of treatment from the start. An early menopause without hormone replacement therapy also raises cardiovascular risk in the long term. A questionnaire such as the Menopause Rating Scale helps the doctor to see which symptom affects a woman most and how it changes with treatment.
How can hot flashes be treated without hormones?
Elinzanetant acts on the temperature control center in the brain. In the randomized OASIS-4 trial (New England Journal of Medicine, 2025), with 474 women on endocrine therapy for breast cancer, elinzanetant reduced hot flashes by about 7.8 episodes a day at 12 weeks, compared with about 4.2 with placebo. The most common side effects were headache, tiredness and sleepiness. Since November 2025, elinzanetant has been approved in the EU also for hot flashes caused by endocrine therapy for breast cancer. Other options are venlafaxine, escitalopram, gabapentin and oxybutynin. In women taking tamoxifen, the doctor avoids paroxetine and fluoxetine, because they weaken the effect of tamoxifen. In a randomized trial (MENOS 1), cognitive behavioral therapy reduced the burden of hot flashes and night sweats in women after breast cancer.
What about the bones?
An early menopause and aromatase inhibitors speed up bone loss. A woman needs a bone density scan at the start of treatment and regularly afterwards, enough vitamin D and calcium, and strength training. In a large analysis (The Lancet, 2015), bisphosphonates in women after the menopause reduced recurrences in the bone by about 28% and deaths from breast cancer by about 18%. Denosumab roughly halved fractures in women taking aromatase inhibitors (ABCSG-18 trial).
What if the cancer is not hormone-dependent?
The ban on hormone replacement therapy does not apply to every cancer. After lymphoma, leukemia, most cervical cancers, or risk-reducing removal of the ovaries in BRCA carriers without breast cancer, hormone replacement therapy is usually possible. When menopause comes before the age of 40 or 45, ESHRE recommends hormone replacement therapy at least until the average age of natural menopause, about 51. This protects the bones, the heart and the brain. The woman, the doctor and the oncologist always decide together. Which cancers allow hormone replacement therapy and which do not is described in the article Menopausal hormone replacement therapy.
The practice's approach
The doctor assesses each symptom separately, together with the type of cancer and the current treatment, and chooses the treatment in cooperation with the oncologist. The doctor asks every woman about sleep, sexual life and mood, because these often weigh more heavily than hot flashes, and monitors weight and metabolism from the start. After chemotherapy, the doctor checks whether the ovaries are still working and discusses contraception with the woman.
After breast cancer, the practice does not give systemic hormone replacement therapy and uses evidence-based non-hormonal treatments. The aim of the practice is for the woman to live well after cancer, safely, and with her own decision on every treatment.
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