Missed Cancer Prompts Call for Breast Density Reporting in NZ Screening

Dionne Scott, a woman from Whanganui, found a lump in her breast nine months after a routine mammogram had come back without finding anything. That gap, and what she did about it, is now the basis of her call for New Zealand women to be told how dense their breast tissue is.

Scott was diagnosed in 2024, at 50. The lump was still there six months after she first noticed it, so she went back to her GP, who referred her for a second mammogram and an ultrasound. Neither test picked up the cancer. But the lump could still be felt, and Scott insisted on a biopsy. That biopsy found breast cancer. She went on to have a lumpectomy, followed by radiation and hormone treatment.

She has no doubt about what pushing for the biopsy meant. Had she accepted the advice to wait another year, she said, she is sure the cancer would have been well beyond grade two by then.

Scott has extremely dense breasts, as an estimated one in 10 women do. For those women, standard mammograms may detect only around half of cancers. Scott says that if she had known dense breasts both raise the risk of breast cancer and make tumours harder to see on a mammogram, she would have paid for extra testing privately.

The Breast Cancer Foundation says her experience is not isolated. Chief executive Vanessa Sorenson said the charity is hearing more often from women whose cancers were missed on mammograms and who learned only after diagnosis that their breasts were dense. She said mammograms remain the best screening tool for most women, but they do not work well for everyone, and the one-size-fits-all approach has failed some. Women are not routinely told their density through the public screening programme, and there is no publicly funded extra screening for women with dense breasts based on their risk.

Sorenson explained the problem plainly: on a mammogram, tumours in very dense tissue show up white, so they cannot be seen. She stressed that mammograms are still incredibly important.

The foundation has put three asks to the next government in its 2026 Election Manifesto. It wants BreastScreen Aotearoa required to include breast density in every screening result. It wants funded additional screening for women identified as higher risk. And it wants a phased rollout of contrast-enhanced mammography, known as CEM, where clinically appropriate. CEM uses an injected contrast dye to make areas of unusual blood flow more visible, helping radiologists spot possible cancers. Sorenson said research shows it can find cancers in dense tissue that are hard to see on a standard mammogram.

Sorenson argued that telling women their density is only a first step, and that reporting should begin as soon as possible, alongside work to decide what screening higher-risk women should get. Without a funded pathway, she said, women who can afford it may get extra screening while others cannot, and access should depend on clinical risk rather than a bank balance.

She pointed to other countries as precedent. Density reporting is mandatory at the federal level in the United States and largely standardised or required across most Canadian provinces and territories. Australia has been introducing it progressively across states, with women found to have high density advised to discuss their overall risk and screening options with their GP.

What to watch is whether political parties take up the manifesto's asks in the lead-up to the 2026 election, and whether reporting and a funded pathway are treated as a package.