Atypical Hyperplasia and Breast Cancer Risk

Atypia and Hyperplasia

Hyperplasia is an abnormality in cell growth which results in a greater number of cells forming in the ducts or lobules of the breast, but without other abnormality. Atypia is a term which denotes the presence of significant abnormality in the appearance of the cells or the way they are arranged, as compared to normal cells. Atypia and hyperplasia can occur independent of each other, and are considered reversible, though the exact mechanisms by which they revert to normal are unknown.

A diagnosis of either hyperplasia or atypia need not always mean that the person has cancer, or even develop cancer in the future. Women with atypia have 1% increased risk of developing cancer compared to women without atypia. Those who do not develop cancer within 10 years of receiving a diagnosis of atypia are said to have significantly lower cancer risk. A repeat biopsy of the same portion of the breast from which the earlier diagnosis was made might even show completely normal cells.

Atypical Hyperplasia

Atypical hyperplasia is described as an accumulation of abnormal cells in the breast. It is not cancer, but can be a pre-cancerous condition. In other words, the abnormal cells that cause atypical hyperplasia keep dividing and piling up, and may eventually result in non-invasive or invasive breast cancer.

Thus, one of the main complications of atypical hyperplasia is an increased long-term risk of breast cancer. Women diagnosed with atypical hyperplasia are at 4 times higher risk of breast cancer than women without it. This remains the same whether the atypical hyperplasia is seen in the ducts or within the lobules.

Research shows that the increase in the risk of developing breast cancer risk in the years following a diagnosis of atypical hyperplasia is:

  • About 7 out of 100 women diagnosed with atypical hyperplasia may develop breast cancer within 5 years post-diagnosis.
  • About 13 out of 100 women diagnosed with atypical hyperplasia may develop breast cancer within 10 years after diagnosis.
  • About 30 out of 100 women with atypical hyperplasia may go on to develop breast cancer within 25 years post-diagnosis.

A diagnosis of atypical hyperplasia at younger ages may be linked to an increase in the risk of developing breast cancer during the lifetime of the patient. It is important to discuss your risk of developing breast cancer with your physician. Understanding one’s cancer risk clearly aids in making critical decisions about cancer screening and risk-reducing medications.

Atypical Hyperplasia and Breast Cancer Screening

Special breast cancer screening recommendations are in place for women diagnosed with atypical hyperplasia. These are intended to help in catching the development of breast cancer, if any, at an early stage, when it can be treated easily and successfully.

According to National Comprehensive Cancer Network (NCCN) recommendations, women with atypical hyperplasia should have a clinical breast examination every 6 to 12 months after 30 years of age, and have a mammogram once a year starting at age 30 years. They should also discuss further follow-up, depending on their previous results, with their health care providers.

According to American Cancer Society (ACS) breast cancer screening recommendations, women diagnosed with atypical hyperplasia do not need clinical breast examination, but should have a mammogram every year and keep their health care providers up to date about their risk.

Cancer Risk Reduction in Women with Atypical Hyperplasia

Women having atypical hyperplasia can be treated with drugs that reduce their risk of developing breast cancer. Tamoxifen and raloxifene are the 2 main FDA-approved drugs used in such cases, both of which are taken in pill form. Tamoxifen is a hormonal drug that can be used in both the prevention and treatment of breast cancer, while raloxifene can lower the breast cancer risk but cannot treat it.

While tamoxifen can be used in both pre- and postmenopausal women, raloxifene is used only in postmenopausal women. However, both tamoxifen and raloxifene have some short-term side effects such as leg cramps, hot flashes, irregular periods, and vaginal dryness. They also carry potential health risks such as venous thrombosis, pulmonary emboli, uterine cancer, or stroke.


Further Reading

Last Updated: Feb 26, 2019

Susha Cheriyedath

Written by

Susha Cheriyedath

Susha is a scientific communication professional holding a Master's degree in Biochemistry, with expertise in Microbiology, Physiology, Biotechnology, and Nutrition. After a two-year tenure as a lecturer from 2000 to 2002, where she mentored undergraduates studying Biochemistry, she transitioned into editorial roles within scientific publishing. She has accumulated nearly two decades of experience in medical communication, assuming diverse roles in research, writing, editing, and editorial management.


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