New Study Discovers Breast Cancer Recurrence 20 Years After Initial Diagnosis
등록일 2019년 01월 07일 목요일
수정일 2017년 11월 09일 목요일

Photo By SewCream via Shutterstock

A breast cancer type that feeds on estrogen may return 20 years after the diagnosis, according to a new study.Researchers from the Early Breast Cancer Trialists' Collaborative Group analyzed data from 88 clinical trials, which involved 62,923 women with estrogen-receptor-positive breast cancer.The women were given hormone therapy for five years and were free from the disease after stopping the treatment.But, a number of women from the clinical trials reported that their cancer had spread throughout the body after 15 years, and some 20 years after the initial diagnosis.

"Even though these women remained free of recurrence in the first five years, the risk of having their cancer recur elsewhere (for example in the bone, liver or lung) from years 5 to 20 remained constant," said Dr.Daniel F.Hayes, senior author of the study and a professor of Breast Cancer Research at the University of Michigan Comprehensive Cancer Center.

The cancer recurrence was directly connected to the characteristics and size of the original cancer.Some of these women faced the highest risk of recurrence of 40 percent distant cancer recurrence over the next 15 years, and the cancer cells have spread in least four lymph nodes.For women with small, low-grade cancers and no spread to the lymph nodes had ten percent risk of distant cancer recurrence over the next 15 years.

"It is remarkable that breast cancer can remain dormant for so long and then spread many years later with this risk remaining the same year after year and still strongly related to the size of the original cancer and whether it had spread to the nodes," said Dr.Hongchao Pan, lead author of the study from Oxford University.

The drug called tamoxifen is known by doctors that significantly reduces recurrence by almost 50 percent during treatment and nearly 30 percent over the next five years.Another drug called aromatase inhibitors that work only in post-menopausal women are more effective than tamoxifen in reducing recurrence and death from breast cancer.An additional five years under hormone therapy substantially reduces any recurrence and possibility of death from breast cancer.But an inquiry comes to mind if a patient should continue endocrine therapy for the next ten years to ensure cancer-free life – what are the side effects of long-term hormone therapy?

"As we look at extending endocrine therapy for 10 years, we wanted to determine whether there were certain subgroups of women whose risk of recurrence was so low they might not need to continue endocrine therapy after five years," said Hayes.

The researchers divided the patients to determine those with the best prognosis, patients with small and less-aggressive tumors that have never spread to the lymph nodes.These women still have recurrence rates between 5 to 20 years at about one percent per year or 10 percent over the course of 15 years.The data suggested that women with ER-positive breast cancer should consider extended hormone therapy beyond five years.Hormone therapies can affect the quality of life of the patient but side effects are rarely life-threatening, according to the researchers.

Hormone Therapy for Breast Cancer

There are some breast cancers that feed on hormones in the blood.Both estrogen-receptor-positive and progesterone-receptor-positive breast cancer cells have receptors or proteins that attach to estrogen or progesterone that helps them grow.Hormone therapy is used to treat these types of breast cancer.The treatment also reaches cancer cells in every part of the body.Clinicians recommend hormone therapy after surgery to prevent recurrence of breast cancer that is usually effective for at least five years.It can also be used for breast cancers that came back and have spread in different parts of the body.

1.Tamoxifen is a drug that stops estrogen from attaching to the cancer cells.While it acts as an anti-estrogen to tumors, it acts like an estrogen to other parts of the body like the bones and the uterus.Common side effects of tamoxifen include hot flashes, fatigue, depression, mood swings, and hair thinning.

2.Fulvestrant is a drug that blocks and damages estrogen receptors and is used to treat metastatic breast cancer.Common side effects of fulvestrant include headaches, appetite loss, breathing issues, hot flashes, and weakness.

3.Aromatase inhibitors are drugs that prevent estrogen production.These drugs are useful for women who are past menopause.Common side effects of AI include night sweats, hot flashes, pain in the joint and muscles, loss of bone mineral density, and vaginal dryness.

4.Ovarian suppression shuts down the ovaries to stop the main source of estrogen and allow some medications like AIs to be used by the patient.When the ovaries are suppressed, the patient may experience menopausal symptoms, such as irregular periods, vaginal dryness, chills, sleeping problems, and mood changes.

5.Megestrol acetate is a drug containing progestin, a man-made form of the hormone progesterone.It interferes with the normal estrogen cycle and disrupts cell growth of cancer cells dependent on tumor cells.

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