A woman's life was turned upside down when a routine mammogram gave her the all-clear, only for her to be diagnosed with an aggressive form of breast cancer less than a year later. The cancer was likely present during the initial scan but was hidden by a common condition.
The All-Clear That Wasn't
In 2019, Krysty Sullivan attended a routine mammogram screening and was told her results were clear. Just eleven months later, she discovered a lump. Medical investigations revealed two tumours, each measuring more than 2cm.
Sullivan, who was 48 at the time, received a diagnosis of triple-negative breast cancer, a challenging type to treat as the cancer cells do not respond to standard targeted therapies.
"It's always a shock to hear that you have breast cancer, but to learn that I had it months after I had a clear mammogram … it was like the earth shifted," Sullivan recalled. "I was left wondering what I had missed."
The Hidden Factor: High Breast Density
What Sullivan had not been told after her mammogram was that she has the highest category of breast density, classified as Bi-rads D. This means her breasts contain very little fatty tissue.
This condition significantly lowers the sensitivity of a mammogram, making it much harder for the imagery to detect small abnormalities like early-stage cancers. She was also unaware that having dense breasts (Bi-rads C or D) slightly increases a person's overall risk of developing breast cancer.
Following her diagnosis, Sullivan underwent a double mastectomy and 16 rounds of chemotherapy. Her doctors believe it is likely the cancers were present during her initial mammogram but remained undetected because of her breast density.
New National Guidelines for Better Care
In a pivotal move, new national guidelines for GPs were released by the Australian federal health department. These guidelines state that patients like Sullivan should be informed if a mammogram shows they have dense breasts.
Furthermore, GPs are to be given additional guidance on how to respond. For patients with the highest density category (Bi-rads D), the guidelines advise that additional imaging should be considered.
The guidance also instructs GPs to ask women with high breast density about other risk factors, such as family history. Depending on the overall risk level calculated, these women might be offered additional screening covered by Medicare.
Dr Anna Withanage Dona, a University of Melbourne research fellow involved in developing the guidance, emphasised its importance. "Up until now, the guidance available to GPs has been pretty inconsistent," she said.
"These guidelines will give doctors better tools and help them explain what breast density means for each individual person, and when to consider further tests or a formal risk assessment."
She added that the guidelines are designed to prevent unnecessary over-screening and avoid causing undue anxiety, noting that "having high breast density is not to say someone will develop breast cancer."
The goal is not to send every woman with dense breasts for more tests, but to help identify those who would genuinely benefit from additional care, especially if they have other risk factors.
The Royal Australian College of General Practitioners' breast medicine chair, Dr Katrina Tiller, welcomed the guidance, calling it a "nuanced area" where GPs need support to provide evidence-based advice.
Sullivan, who contributed to the guidelines as a consumer representative for the Breast Cancer Network Australia, expressed her hope for the future. "I think it's really going to empower women to have important conversations with their doctors and get the personalised care that they need," she said.
