Mammography involves detailed X-ray images of the breast that may detect tumors too small to feel. Stage 1 breast cancer is the earliest stage and is often easier to treat than later-stage breast cancer.

Mammograms can detect stage 1 breast cancer. According to the American Cancer Society, regular mammograms are helpful in detecting early-stage breast cancer before you have symptoms. And breast cancer found during screening mammograms is usually smaller and hasn’t spread outside the breast.

But mammography is not perfect. According to the National Cancer Institute, screening mammograms miss about 20% of breast cancers that are present during screening.

This article takes a look at what mammograms typically detect, symptoms of stage 1 breast cancer, and screening recommendations.

The radiologist will look for breast changes such as calcifications and other abnormal areas. Breast cancer appears white on the scan and may show up as:

  • a solid mass
  • areas that look different from healthy breast tissue (asymmetries)
  • areas that appear distorted or pulled toward a certain point

If you’ve had a mammogram before, the radiologist will compare the new scans to the old ones. This can help determine if suspicious areas were there before and whether they’ve changed at all.

It’s not always easy to see early-stage breast cancer on a mammogram. About half of women have dense breasts. That means the breasts have more fibrous and glandular tissue in relation to fatty tissue. Dense breast tissue also shows up as white on a mammogram, making it a bit harder to detect breast cancer.

Your doctor will likely recommend an ultrasound following a mammogram with unclear results. Research suggests that screening ultrasound is effective in detecting cancer in people with dense breast tissue. However, there’s no consensus on whether women with dense breasts should have regular screening ultrasounds.

If you have dense breast tissue, your doctor can make a recommendation based on your breast cancer risk factors.

Most people with stage 1 breast cancer don’t have symptoms, and the mass is small enough that you’re unlikely to notice. But depending on its location within the breast, you might find it by accident or when performing a breast self-exam.

Other warning signs of breast cancer are:

  • lump under the armpit
  • an area of the breast that’s thickening, swelling, or dimpling
  • nipple changes, such as redness, pulling, or discharge
  • any changes in size or shape of the breast
  • breast or nipple pain

Is breast cancer slow or fast growing?

Different kinds of breast cancer grow at different rates. Tumors are graded on a scale of 1–3, with 1 being slower growing and 3 being the most aggressive.

Grade 1 tumors tend to be hormone receptor-positive. Some research suggests that the fastest growth rates are associated with triple-negative breast cancer, followed by HER2-positive breast cancer.

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Cancer is serious, but stage 1 breast cancer is highly treatable and survivable.

  • Stage 1 means the tumor is 2 centimeters or smaller.
  • In stage 1A, the tumor has not spread beyond the breast.
  • In stage 1B, a tiny number of cancer cells have made their way to nearby lymph nodes.

Based on data from 2013–2019, the 5-year relative survival rate for localized breast cancer is 99.3%. Factors that can affect the outlook for someone in stage 1 breast cancer treatment include:

  • the specific type of breast cancer, including hormone and HER2 receptor status
  • the tumor grade
  • your age and overall health

Screening means looking for cancer in someone without symptoms. The U.S. Preventive Services Task Force recommends screening mammography every other year for women ages 50–74 who are at average risk for breast cancer.

Your doctor may recommend earlier or more frequent screening if you’re at higher-than-average risk for breast cancer.

What are the risk factors for breast cancer?

Most diagnoses occur after age 50. Besides age and being female, other breast cancer risk factors are:

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Mammograms can detect stage 1 breast cancer, though it does miss some.

Early-stage breast cancer is very treatable, but it’s worth noting that some types are more aggressive than others. Since you may not have symptoms at this stage, screening mammography is a good way to find it before it grows and spreads.

With treatment, the outlook for stage 1 breast cancer is very favorable. Consider speaking with a doctor about your breast cancer risk factors and screening recommendations. And be sure to let a doctor know if you have signs or symptoms between screenings.