What Is Breast Cancer? Symptoms, Causes, Diagnosis, Treatment, and Prevention
CancerBreast Cancer

What Is Breast Cancer? Symptoms, Causes, Diagnosis, Treatment, and Prevention

What Is Breast Cancer? Symptoms, Causes, Diagnosis, Treatment, and Prevention
Everyday Health
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Updated on February 28, 2026
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Breast cancer is a disease that starts in the breast with a malignant tumor. A malignant tumor is a mass of cells that grows out of control. The cancerous cells can also metastasize, or move to other tissues or parts of the body. The cancer can develop in any of the three types of breast tissue: lobules, ducts, and connective tissue.

Most cancer begins in the lobules (the milk-producing glands), or in the ducts, along which milk travels to the nipple.

 But tumors can also develop in the fibrous and fatty connective tissue that surrounds the lobules and ducts.
Several different types of breast cancer exist. The type of breast cancer and its stage, or how far it has grown, determine the course of treatment for it. Breast cancer that spreads into normal tissue is called invasive breast cancer. Noninvasive breast cancer stays within the breast lobule or duct.

Types of Breast Cancer and Precancer

DCIS/LCIS: The Slow-Moving Breast Cancers

A biopsy may reveal a noninvasive cancer that is not growing beyond its starting location. These types of cancers are called carcinoma in situ.

“Carcinoma” refers to a cancer that begins in the outer layer of cells around an organ. “In situ” means something stays where it began.

Ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS) are the two types of in situ carcinoma in the breast. Doctors usually find DCIS or LCIS on mammography or other imaging because these cancers rarely have signs or symptoms.

DCIS means abnormal cells exist in the lining of the milk ducts but have not invaded surrounding breast tissue. DCIS can become invasive cancer without treatment.

LCIS occurs in the breast lobules, which produce breast milk, without spreading further. LCIS is not technically cancer, but it is sometimes called precancerous.

LCIS is less common than DCIS but indicates a higher risk of invasive cancer. LCIS may not require treatment beyond observation to see whether breast cancer develops.

Invasive Breast Cancer

Invasive (or infiltrative) ductal carcinoma (IDC) is the most common type of breast cancer and the type most likely to occur in men. It makes up 80 percent of all new breast cancer cases and becomes more common with older age.

Like DCIS, IDC begins in the milk ducts but spreads beyond them into the surrounding fatty tissue. It may continue to spread into the lymph nodes and bloodstream.

Treatment for IDC will depend on the stage, the type of breast cancer, its aggressiveness, and other characteristics. Treatment generally involves a combination of surgery, radiation, chemotherapy, targeted therapy, hormone therapy, and immunotherapy.

Triple Negative and HER-2 Negative Breast Cancer

A subset of women diagnosed with breast cancer will be told that their tumor is triple negative, which means that the cells within the tumor lack receptors on their surface that respond to human epidermal growth factor receptor 2 (HER-2) as well as estrogen and progesterone receptors.

Some of the drugs used to treat breast cancer, which are designed to interact with these receptors, won’t be useful in these cases. Doctors will need to tailor a treatment regimen to other weaknesses in this tumor type.

Prognosis of Breast Cancer

Prognosis depends on the stage of breast cancer and the general health of any given individual. But broadly, rates of death from breast cancer have been decreasing. The majority of women survive this type of cancer. Overall, 92 percent of women will survive at least five years after being diagnosed with breast cancer.

More than four million women in the United States have a history of breast cancer.

Signs and Symptoms of Breast Cancer

If you notice any of the following symptoms, check in with your healthcare provider.

  • Any lump in or near the breast or underarm
  • Warmth or unexplained tenderness in the breast
  • A hardening, thickening, or swelling area in the breast
  • Nipple tenderness without another cause
  • Nipple discharge (except breast milk), especially clear or bloody discharge
  • An unexplained change in the color, texture, size, or shape of the breasts or nipples
  • Skin dimpling on the breast or enlarged pores (like an orange skin)
  • Swelling, redness, scaliness, or general pain in the breast or nipples
  • Nipples that turn inward without explanation
  • Irritated or itchy breasts
  • A rash on the breast, which can be a sign of inflammatory breast cancer
While a lump can be a sign of cancer, nearly 80 percent of lumps found in the breast turn out to be noncancerous.

The most common causes of noncancerous lumps include:

  • Fibrocystic changes as a result of hormonal fluctuations
  • Cysts
  • Benign lumps called fibroadenomas
  • Wart-like growths called intraductal papillomas
  • Fatty tissue that occurs as a result of trauma to the breast

Breast cancer may cause any of these symptoms. Some people experience no symptoms at all.

Illustrative graphic titled Symptoms of Breast Cancer Illustrative graphic titled Symptoms of Early Breast Cancer shows lump in breast/armpit, breast dimpling, breast pain, change in breast size and nipple discharge. Everyday Health logo
Breast cancer may cause any of these symptoms. Some people experience no symptoms at all.

Causes and Risk Factors of Breast Cancer

The biggest risk factors for this disease, besides being female, include:

  • Age — risk starts to rise after age 50
  • A family history
  • Genetics
  • Previous exposure to radiation
Each woman’s risk involves a combination of different factors. If you’re concerned, your doctor can help you assess how great your risk is and whether you need to take any extra precautions with regard to screening.

Genetic Testing for Breast Cancer: BRCA1 and BRCA2

In some cases, particularly if you have a family history of breast or ovarian cancer, a doctor may suggest genetic testing for two of the most common gene mutations known to increase risk for developing these cancers: BRCA1 and BRCA2. Inherited BRCA gene mutations cause about 5 to 10 percent of breast cancers and about 10 to 15 percent of ovarian cancers.

There are other genes implicated in breast cancer risk, though they are much rarer than the BRCA mutations.

Ovarian Cancer

Most breast and ovarian cancers don’t develop due to genetic mutations — but mutations in the BRCA1 and BRCA2 genes, which increase the risk of breast cancer, also increase the risk of ovarian cancer in women.

Women with a family history of these cancers may want to consider genetic testing.

Periodontal Disease

Recent research has identified potential genetic links between periodontitis and breast cancer, and some studies suggest that higher levels of gum inflammation, known as the gingival index, may have links to an increased risk of the disease.

Breast cancer is a complex disease that starts in the breast and can spread, but early detection and tailored treatments improve outcomes. Noticing signs like lumps, nipple discharge, or changes in breast appearance should prompt a checkup with your healthcare provider. Regular screenings and prioritizing a healthy lifestyle are key to managing your risk.

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Understanding Breast Cancer Risk

How Is Breast Cancer Diagnosed?

Doctors can screen for breast cancer using a mammogram. A mammogram is an X-ray with low-dose radiation that lets doctors look for abnormalities in the breast tissue.

Doctors may also use magnetic resonance imaging (MRI), ultrasound, or 3D mammography (breast tomosynthesis) to further evaluate suspicious mammogram findings or inconclusive results, such as in cases of extremely dense breast tissue.

An MRI uses a large magnet to create images of the breast. An ultrasound sends sound waves into the breast, creating an image when they bounce back. A 3D mammogram uses X-rays like a regular mammogram, but it takes multiple image slices of the breast at different angles to construct a 3D image.

Screening tests look for possible signs of breast cancer but cannot diagnose it. If doctors see a suspicious lump or mass of cells, they may use some of those same tests to get a closer look at the abnormal area. A diagnostic mammogram provides more detail in the image of the breast.

The only way to make a certain diagnosis of breast cancer is a biopsy. A biopsy involves removing some breast tissue from the suspicious area and looking at the cells under a microscope.

During diagnosis, doctors also work out the stage of breast cancer. They use stages of breast cancer to describe how far along the cancer has grown or spread. Stages range from 0 to 4 (often expressed in Roman numerals, I to IV). Each stage has further subcategories of A, B, or C.

Stage 0 The cancer is noninvasive and shows no evidence of leaving the part of the breast where it began. One type of stage 0 cancer is ductal carcinoma in situ (DCIS).

Stage 1 The cancer cells are spreading to surrounding breast tissue, but the group of cancer cells or the tumor remains very small. It is usually easily treatable.

Stage 2 The cancer has begun to grow but it remains only in the breast or nearby lymph nodes. Treatment is not usually very difficult.

Stage 3 The cancer has begun invading lymph nodes, muscle, and other body tissue near the breast, but it has not reached organs farther away. Treatments vary according to the person and type of breast cancer.

Stage 4 The cancer is very advanced and has spread to several organs or other parts of the body. Stage 4 breast cancer is considered incurable, but women may live several years or more with ongoing treatment.

Finding Your Best Treatment Team

After receiving a diagnosis, you will have several decisions to make about the healthcare providers who will handle your treatment.

Perspectives
Portrait of a person
Brianna
Breast cancer previvor
“Being able to know your options, know what's available to you, because of another person, is everything. I wouldn't be here today without that.”
Transcript Available

Cancer treatment usually involves a team of people, such as a surgeon, a medical oncologist, a nurse practitioner, a counselor, a patient navigator, and specialists associated with your cancer type.

Factors to consider in choosing your oncologist and treatment team are their expertise in your cancer type, what your insurance will cover, your ability to travel to and from appointments and procedures, and recommendations from others.

Even after you have a treatment team, it is a good idea to look for another oncologist to get a second opinion about your diagnosis and treatment options. It is acceptable and sometimes common to change doctors during your treatment if you need to.

Breast Cancer Prognosis

People can have different outlooks depending on the type and stage of breast cancer and how they respond to treatment. Different treatment plans follow different timetables. Depending on your individual needs, you may need to take time off from work to recover from surgery or a cycle of chemotherapy.

Recurrent breast cancer is breast cancer that returns after initial treatment; it may occur months or years after your initial treatment.

The highest risk of recurrence is during the first two years after treatment, though the majority of patients won’t experience recurrence.

There’s currently no cure for metastatic breast cancer (stage 4 breast cancer that has spread to other parts of the body) but with treatment to control it, many patients with the disease now live productive, fulfilling lives for years.

Treatment and Medication Options for Breast Cancer

A treatment plan will depend on what type and stage of breast cancer you have and how aggressive it is.

Breast cancer treatment most commonly involves surgery, often along with treatments to help rid the body of cancer cells or ensure that it remains cancer-free.

Surgical treatments includelumpectomy, in which a surgeon removes a small portion of the breast (where the tumor is located). Your surgeon may remove more tissue from the lumpectomy site to make sure they’ve treated all of the diseased tissue.

A mastectomy is the removal of one or both breasts and may include the removal of lymph nodes and armpit tissue.

Along with surgery, a cancer care team may recommend radiation to destroy cancer cells that remain in the area. Women who have surgery that removes the lump but preserves as much breast tissue as possible (known as breast conservation) generally have radiation therapy afterward to reduce the risk of the cancer coming back.

Most women who have had all or part of a breast removed can have reconstructive surgery for their breast (or breasts), to match the size and shape of the other breast (or their original breasts).

Medication Options

A range of medications, involved in chemotherapy, hormone therapy, and biologic targeted therapy, can help to treat breast cancer. Doctors consider these medication regimens to be systemic treatment, since they affect cells throughout the body.

Chemotherapy involves a combination of drugs used to destroy cancer cells or slow their growth. Doctors can give chemotherapy before or after breast cancer surgery.

Your doctor will determine if chemotherapy is right for you based on the type and size of tumor you have, the degree to which the breast cancer has spread to the lymph nodes, and the risk of the cancer spreading.

   Poll

What’s the most impactful emotional challenge after breast cancer treatment?

If your type of cancer is found to be sensitive to hormones, you may need hormone therapy, which interferes with the body’s ability to produce or use hormones, thereby slowing or stopping the growth of tumors.

Hormone therapy for cancer is not the same as hormone therapy for menopause.

Hormone therapy treatments include:

  • Medications called selective estrogen receptor modulators (SERMs), which block hormones from attaching to cancer cells.
  • Aromatase inhibitors, which stop the body from making estrogen after menopause.
  • Faslodex (fulvestrant), which targets estrogen receptors for destruction.

A cancer specialist may also recommend the removal of the ovaries or prescribe medications that stop the ovaries from making estrogen.

Biologic targeted therapy uses drugs that can alter the behavior of breast cancer cells.

Immunotherapy uses medications to stimulate the body’s immune response in order to recognize and eliminate cancer cells. Immunotherapy may play a role in some forms of breast cancer.

Complementary and Integrative Therapies

In addition to medical interventions, you may want to consider complementary therapies, particularly to help manage symptoms and side effects from treatment.

Acupuncture, massage, meditation, mindfulness, and visualization may help reduce stress, anxiety, and fatigue, boost sleep, relieve pain and nausea, and improve mood.

Lifestyle Changes and Prevention of Breast Cancer

Eat a Healthy Diet

A healthy diet helps your body remain strong while you undergo breast cancer treatments. Your diet can help your body rebuild damaged tissue, reduce therapy side effects, and reduce the risk of infection.

A healthy diet includes a variety of vegetables, fruits, whole grains, dairy, and lean, high-protein foods, such as chicken, fish, legumes, and beans. Getting enough calories each day is vital, even if you don’t feel like eating.

Some breast cancer treatments may have side effects that make it difficult to eat well. These side effects may include nausea, vomiting, constipation, diarrhea, dehydration, a sore mouth or throat, weight gain, or changes to your sense of taste or smell.

Your doctor can help you identify strategies to treat these side effects, reduce their impact, and eat as healthfully as possible despite them.

Foods to avoid during breast cancer treatment include alcohol, fried or greasy foods, and foods with high amounts of fat or sugar.

Stay Active

There was a time when doctors may have told women with breast cancer to rest, and exercise was an afterthought.

But a growing body of research suggests that a reasonable exercise program not only won’t hurt but might actually benefit patients by relieving treatment-related fatigue, depression, and pain. Physical activity might also reduce the risk of a painful buildup of fluid in the lymph nodes called lymphedema, as well as making the cancer’s return, known as recurrence, less likely.

Prevention of Breast Cancer

While you can’t change certain risk factors, such as your family history or your age, research shows that there are a number of lifestyle modifications you can make to reduce your risk of breast cancer, even if you’re at high risk.

Try to limit yourself to less than one alcoholic drink a day, and don’t smoke.

Control your weight — being overweight or obese increases your risk of breast cancer, particularly after menopause. Exercise can help you maintain a healthy weight. The American Cancer Society recommends that adults get 150 to 300 minutes of moderate-intensity activity each week (or 75 to 150 minutes of vigorous-intensity activity), ideally spread throughout the week.

Women who breastfeed for at least several months may also lower their risk.

Hormone therapy to alleviate symptoms during menopause can increase your risk of breast cancer. Consider nonhormonal options or use the lowest dose that works for you.

Try to avoid exposure to radiation and environmental pollution. Medical imaging methods, such as computed tomography, use high doses of radiation. While more studies are needed, some research suggests a link between breast cancer and cumulative exposure to radiation over your lifetime.

Reduce your exposure by having such tests only when absolutely necessary.

Women who are at an increased risk of breast cancer because of a family history or because genetic testing has revealed a mutation in their BRCA1 or BRCA2 gene should opt for closer monitoring by their healthcare provider and consider taking certain medications that may reduce the risk in certain high-risk women. For women with a very high risk, preventive surgery is an option to consider.

Complications of Breast Cancer

As with treatment, possible complications of breast cancer depend on the type and stage of breast cancer you have. A number of complications are side effects of treatment, which may continue after treatment stops. Depending on what kind of treatment you’ve had, these can include:

Some patients develop a chronic condition called lymphedema after treatment. Lymphatic fluid builds up in the tissues, causing swelling. Lymphedema usually results from the removal of lymph nodes or damage to them.

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A Breast Cancer Crisis in the Black Community

Caleen Allen of Sisters Network explains why describing breast cancer as a crisis for Black women is not an exaggeration — it’s a hard truth.

Research and Statistics: Who Has Breast Cancer?

Breast cancer makes up about 32 percent of new cancer diagnoses in women.

The rate of breast cancer cases has been gradually increasing since the mid-2000s, as cancer teams have been diagnosing these cancers at an early stage more often. Hormone receptor-positive disease diagnoses have also increased breast cancer diagnoses.

About 1 in 8 women (about 12.4 percent of women) will have an invasive breast cancer diagnosis at some point in their lives.

Breast cancer can occur in anyone with breast tissue, but it’s much rarer in men than in women. Fewer than 1 in 100 breast cancers develop in men.

The disease is more common in middle age. About 16 percent of women with breast cancer are under 50 years of age.

Disparities and Inequities in Breast Cancer

The incidence of breast cancer overall is slightly higher for white women than Black women, but in women under 45, breast cancer is more common in Black women. Black women are also more likely to die from breast cancer than women of other races or ethnicities.

At least some of this increased risk is due to less access to follow-up care after an abnormal mammogram and lower rates of health insurance.

FAQ

What is breast cancer?
Breast cancer is the result of cancerous cells that grow within breast tissue. Cancers often start in the milk ducts or lobules.
Men have breast tissue, and therefore, they are able to develop breast cancer, though it is rare.
October. Watch for pink ribbons, which people use to promote breast cancer awareness.
Often, there is no external sign of breast cancer. But some visual cues may include a change in the look or feel of the breast or nipple, or nipple discharge.
A lump in the breast is the most common symptom of breast cancer, and it is usually painless.

Resources We Trust

EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
  1. Breast Cancer Basics. Centers for Disease Control and Prevention. November 5, 2024.
  2. Understanding Your Pathology Report. Breastcancer.org. December 6, 2025.
  3. Your Pathology Report: Lobular Carcinoma In Situ (LCIS). American Cancer Society. July 7, 2023.
  4. DePolo J. Lobular Carcinoma in Situ (LCIS) and Atypical Lobular Hyperplasia. Breastcancer.org. August 15, 2023.
  5. DCIS (Ductal Carcinoma In Situ). Breastcancer.org. October 30, 2025.
  6. Invasive Ductal Carcinoma (IDC). Breastcancer.org. December 5, 2024.
  7. Triple-Negative Breast Cancer (TNBC). Breastcancer.org. January 8, 2026.
  8. Survival Rates for Breast Cancer. American Cancer Society. January 13, 2026.
  9. Breast Cancer Facts and Statistics. Breastcancer.org. February 5, 2026.
  10. Symptoms of Breast Cancer. Centers for Disease Control and Prevention. July 30, 2025.
  11. Breast Cancer. Mayo Clinic. July 26, 2025.
  12. Levy R. What Does a Breast Lump Feel Like? Dana-Farber Cancer Institute. February 16, 2024.
  13. Breast Cancer Risk Factors You Can’t Change. American Cancer Society. December 16, 2021.
  14. Hereditary Breast Cancer and BRCA Genes. Centers for Disease Control and Prevention. October 10, 2024.
  15. What Causes Hereditary Breast and Ovarian Cancers. Centers for Disease Control and Prevention. September 23, 2025.
  16. Genetic Counseling and Testing for Breast Cancer Risk. American Cancer Society. December 16, 2021.
  17. Wu E et al. Identification of potential shared gene signatures between periodontitis and breast cancer by integrating bulk RNA-seq and scRNA-seq data. Scientific Reports. April 2, 2025.
  18. Breast Cancer: Diagnosis and Treatment. Mayo Clinic. July 26, 2025.
  19. 3D mammogram. Mayo Clinic. October 24, 2024.
  20. Mammograms: What You Need to Know. Breastcancer.org. January 7, 2026.
  21. Breast Biopsy. Breastcancer.org. March 9, 2024.
  22. Breast Cancer Stages and Staging. Susan G. Komen. December 21, 2023.
  23. Fitting Breast Cancer Treatment Into Your Schedule. Breastcancer.org. June 29, 2022.
  24. Recurrent Breast Cancer. Mayo Clinic. April 19, 2024.
  25. Lange J. Johns Hopkins Medicine. Breast Cancer Recurrence.
  26. Canzoniero JV. Metastatic Breast Cancer. Johns Hopkins Medicine. Canzoniero JV.
  27. Treating Breast Cancer. American Cancer Society.
  28. Having radiotherapy for breast cancer. Cancer Research UK. July 3, 2023.
  29. Hormone Therapy for Breast Cancer. American Cancer Society. September 28, 2025.
  30. Immunotherapy for Breast Cancer. American Cancer Society. October 27, 2021.
  31. Alternative cancer treatments: 11 options to consider. Mayo Clinic. January 21, 2026.
  32. How and What to Eat When You Have Treatment-Related Side Effects. Breastcancer.org. November 22, 2022.
  33. Exercise and Breast Cancer. Breastcancer.org. January 15, 2026.
  34. Can I Lower My Risk of Breast Cancer? American Cancer Society. December 16, 2021.
  35. Breast Cancer Prevention: How to Reduce Your Risk. Mayo Clinic. December 1, 2023.
  36. Di Maria S et al. Understanding the risk of ionizing radiation in breast imaging: Concepts and quantities, clinical importance, and future directions. European Journal of Radiology. December 1, 2024.
  37. Late Effects of Treatment. Susan G. Komen. April 15, 2024.
  38. Lymphedema. Mayo Clinic. November 24, 2022.
  39. Yedjou CG et al. Health and Racial Disparity in Breast Cancer. Advances in Experimental Medicine and Biology. January 3, 2020.
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Ryland J. Gore, MD, MPH

Medical Reviewer
Castle Connolly Top Doctor
Ryland Gore, MD, MPH, is a board-certified, fellowship-trained surgeon specializing in breast surgical oncology in Atlanta. She completed her general surgery residency at Rush University Medical Center and John H. Stroger Cook County Hospital in Chicago. She went on to complete her breast surgical oncology fellowship at Maimonides Medical Center in Brooklyn, New York.

In addition to her professional responsibilities, Gore previously served on the board of directors for Every Woman Works, an Atlanta-based nonprofit organization whose mission is to empower women and help them transition into independence and stability from common setbacks. Gore served as the chairwoman of the American Cancer Society’s Making Strides Against Breast Cancer campaign in Atlanta for three years (2019 to 2021). She is currently the co-director of Nth Dimensions’ Strategic Mentoring Program and the alumni board chair of the Summer Health Professions Educational Program (SHPEP), which is a collaborative effort by the Robert Wood Johnson Foundation, Association of American Medical Colleges, and the American Dental Education Association.

Gore is a highly sought after speaker, consultant, and lecturer on breast cancer and breast health, as well as women’s empowerment topics.
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Tara Haelle

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With two decades of reporting experience under her belt, Tara Haelle has written for a range of publications, including National Geographic, The New York Times, Texas Monthly, Science News, NPR, Washington Post, Scientific American, Politico, Parents, WebMD, Self, O Magazine, and Wired.

She specializes in writing about public health and medical research, particularly vaccines, infectious disease, maternal and pediatric health, mental health, healthcare disparities, LGBTQIA+ health, misinformation, and parenting. Her trade work covering medical research and medical conferences has appeared in MDEdge, Medscape/WebMD, and Haymarket titles.

A former Forbes and Medium contributor, Haelle regularly blogs at the Association of Health Journalists, where she is the Infectious Disease Beat Leader and former Medical Studies Beat Leader, providing resources and training on responsible journalistic coverage of infectious disease and medical research. Her monthly blog at Science and the Sea, from the University of Texas Marine Science Institute, highlights short stories about marine life.

Haelle’s Vaccination Investigation: The History and Science of Vaccines is a starred Kirkus book. She co-authored The Informed Parent: A Science-Based Resource for Your Child’s First Four Years, and she has written nearly a dozen children’s nonfiction science books. As a professional speaker, she has spoken about vaccine hesitancy at TEDx Oslo and has delivered national and international keynotes, webinars and grand rounds on vaccines and vaccine hesitancy, parenting, understanding medical research, storytelling, and mental health.

Haelle received her master’s in photojournalism from the University of Texas at Austin, and her images have appeared in NPR, Texas Monthly, Science News, the Fort Worth Star-Telegram, Chicago Sun-Times and Women’s Wear Daily. An avid traveler, she has backpacked, hiked, train-hopped, sky-dived, spelunked, scuba-dived and motorbiked through dozens of countries. She lives in Texas with her husband and two sons, four dogs, and 15 pet rats, give or take.
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