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Study: Women With Dense Breast Tissue May Benefit From Regular MRIs

Breast cancer. Coloured sagittal magnetic resonance imaging (MRI) scans of a breast of a 39- year-old woman with breast cancer. The cancer (orange) has been highlighted by the injection of a gadolinium contrast medium, a contrast medium suitable for use in MRI scans. The front of the breast is at left in each scan, in these views from the side. The cancer is a ductal carcinoma, a carcinoma of the ducts that channel milk to the nipple. Ductal carcinoma is a common form of breast cancer. Breast cancer, the most common cancer in women, can be treated by surgical removal of the affected breast, often combined with radiotherapy and chemotherapy.

While there has been some controversy over when women should start getting mammograms, all experts agree that screening is an important first step in detecting breast cancers and treating them early. But for some women, that’s not enough. For the approximately 40% of women with dense breast tissue, and especially the 10% with extremely dense tissue, cancer cells are harder to detect, since the denser tissue can mask small growths. In addition, dense breast tissue itself is also a risk factor for developing cancer.

There’s been debate among experts over whether these women should have additional screening, on top of mammograms. A new study published in the New England Journal of Medicine provides the strongest data yet to support adding MRI screening to mammograms for women with extremely dense breast tissue.

Previous studies have compared rates of breast cancer in women getting mammograms alone to rates in those getting mammograms and MRI, but it hasn’t been clear that the “cancers” identified in these data sets were actually cancer. That’s because some breast cancers are what experts consider a pre-cancerous stage, known as ductal carcinoma in situ, meaning they may not grow or progress into disease.

That’s led some doctors to worry over potential over-diagnosis of breast cancer, which can lead to over-treatment of lesions that may never develop into tumors. The U.S. Preventive Services Task Force, which attempts to find answers to controversial health questions, has concluded that there is not enough evidence to advise women about the benefits or harms of adding other breast-cancer testing on top of mammograms.

In the new study, Carla van Gils, professor of clinical epidemiology of cancer at the University Medical Center Utrecht, attempted to address this concern by focusing on how many actual cancers the combination of mammogram and MRI can help to detect in women with dense breast tissue. Taking advantage of the fact that the Netherlands has a national cancer registry that includes about 99% of all diagnoses in the country, she and her team studied more than 40,000 women with extremely dense breast tissue, who were randomly assigned to screening with mammography alone or both mammography and MRI.

Each woman in the study was screened once in the two year study period (following the Netherlands’ screening guidelines that call for mammograms every other year for women over 50). Van Gils and her team analyzed how many invasive cancers were detected in between screenings, which serves as a measure for how effective the MRI was in detecting what the researchers call interval cancers—those diagnosed after a negative mammogram, and before the next mammogram was scheduled.

“If we can prevent those, we know at least we are preventing clinically relevant tumors,” says van Gils, “and not just over diagnosing.” They found that the rate of such cancers in women getting both types of imaging was 2.5 per 1,000 screenings, compared to 5 in 1,000 for women just getting mammograms.

The idea is that supplementing mammograms with MRI in the initial screening led to earlier detection of tumors that the mammograms missed which in turn contributed to lower cancer rates during a second screening, because presumably the women are seeing their doctors when suspicious growths are found and getting them treated.

The data do not confirm that combining mammograms and MRIs can lead to fewer deaths from breast cancer; that’s something van Gils will study in coming years. But documenting the reduction in cancer detected in between screenings is an important first step in showing the value of supplemental MRI for women with extremely dense breast tissue.

It also supports the reasoning behind a law passed earlier this year in the U.S. requiring that mammogram reports include an assessment of the density of women’s breast tissue, along with an explanation for why that might make mammogram results more difficult to interpret.

Van Gils notes that the results of her study aren’t robust enough yet to recommend that all women with dense breast tissue (even those with extremely dense breast tissue) should get MRIs on top of their regular mammogram screenings. For one, lowering the rates of false positives for MRIs is still a challenge; training radiologists to become more adept are reading images of dense breast tissue could help, as could applying machine learning technology to pick up subtle changes that even the best-trained human eyes cannot.

That said, if longer-term studies—enabling doctors to compare MRI readings over time to track the growth of lesions—also confirm that supplementing mammograms with MRI can lower death rates from breast cancer, it could push experts to change guidelines and give women firmer advice on how best to manage their cancer risk.

By Alice Park

November 27, 2019

Source: Study: Women With Dense Breast Tissue May Benefit From Regular MRIs | Time

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Dr. Amy Degnim, surgeon at Mayo Clinic, explains what dense breast tissue is and different types of imaging that may be recommended for breast cancer screening. To learn more about breast cancer screening, visit: https://mayocl.in/31AZAoC To request an appointment at Mayo Clinic, visit: https://mayocl.in/2QwVBoc Dense breast tissue makes breast cancer screening more difficult due to its appearance on a mammogram. Other imaging used for screening includes 3D mammogram, breast MRI, breast ultrasound and molecular breast imaging (MBI). More health and medical news on the Mayo Clinic News Network. https://newsnetwork.mayoclinic.org/

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A Low-Fat Diet May Lower the Risk of Dying from Breast Cancer

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Breast cancer treatments have come a long way in recent decades, but understanding how to prevent tumors from forming in the first place has been a major challenge.

In a new study being presented at the annual American Society of Clinical Oncology meeting in Chicago next month, researchers report intriguing evidence that a low-fat diet, similar to the kind doctors recommend for heart health, is also linked to a lower risk of dying from breast cancer.

The study analyzed data from the Women’s Health Initiative, a large trial sponsored by the National Institutes of Health that studies the health effects of hormone therapy, diet and certain supplements on the health of more than 160,000 postmenopausal women. In this trial, researchers led by Dr. Rowan Chlebowski, an investigator at LA Biomedical Research Institute at Harbor-UCLA Medical Center, focused on a group of nearly 49,000 women who were randomly assigned to follow either a low-fat diet or a control diet for 8.5 years. The low-fat diet group aimed to reduce their fat intake to 20% of their total daily calories and to increase the consumption of fruit, vegetables and grains. None of the women had breast cancer at the start of the study.

After the study ended, the rates of new breast cancers were about the same in the two groups, but women who were diagnosed with breast cancer in the interim had a 35% lower risk of dying from any cause compared to those on the control diet. Even 20 years after the study ended, the women who ate the low-fat diet continued to have a 15% lower mortality risk. And in the longer follow-up data, their risk of dying specifically from breast cancer was 21% lower than that of the women who didn’t change their diet.

“This is a very exciting result for us,” says Chlebowski. “Now we have randomized clinical trial evidence that dietary moderation, which is achievable by many, can have health benefits including reducing risk of death from breast cancer. That’s pretty good; it’s hard not to be happy about that.”

The study is the first to rigorously test a potential factor that could influence deaths from breast cancer. Earlier observational studies did not assign volunteers to specific diets but looked at cancer outcomes depending on what people, on their own, chose to eat. In this study, volunteers were provided with dietary guidelines to follow about what to eat. “Until this study, we lacked any data from a prospective randomized control trial, which is the gold standard, for showing that a dietary approach really does reduce the risk of dying from breast cancer,” says Dr. Neil Iyengar, a medical oncologist at Memorial Sloan Kettering Cancer Center, who was not involved in the study. “Many of us who are proponents of considering diet and exercise in the cancer treatment plan are excited by this trial data because it is the first to show in a very robust way that we can improve outcomes and prevent cancer-related deaths just by changing the diet.”

In a separate sub-study, the research team also showed that the longer women were on the modified diet, the lower their risk of death during the study period. The results should give doctors more confidence in considering diet when discussing treatment options with women who are diagnosed with breast cancer. While the study did not find a significant connection between dietary changes and the incidence of new breast cancer, the results do suggest that modifying the diet can lower a woman’s risk of dying from any cause, or from breast cancer, if she is diagnosed with the disease.

The reason for that, says Iyengar, may have to do with the diet’s “dose.” It’s possible, for example, that the effect of the dietary change is greater on tiny tumors in the breast tissue that are already established, although they aren’t robust enough yet to lead to a diagnosis of breast cancer. “The effect of this diet may be stronger in preventing the growth of already established tumors rather than preventing the development of tumors,” he says. “What this trial does is position us to take a deeper dive, now that we know we can effectively change the tumor or cancer behavior with diet.”

Chlebowski plans to dig deeper into the data to find out more about how diet is working to lower deaths from breast cancer. During the trial, women provided blood samples both at the start of the study and one year later, so he and his team may find factors that changed among the women on the diet compared to those on the control plan.

In the meantime, he hopes cancer doctors will talk about diet with their patients who might be at higher risk of developing breast cancer. Though not all women in the study were able to lower their fat intake to 20% of their daily calories,“these dietary changes are achievable by many,” he says. Even though not all of the women on the low-fat diet met the target, the study showed that the modifications still reduced risk of dying from any cause and from breast cancer. “It’s about taking smaller pieces of meat, and adding vegetables to the plate to balance things out,” he says.

By Alice Park

Source: https://time.com/

 

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