Radiation therapy provided no benefit for women over age 60 on hormone therapy with luminal A subtype breast cancer

The least aggressive breast cancer subtype (luminal A) occurs in women of all ages, but is more prevalent in older women.

Previous studies have shown that radiation therapy is of overall benefit for women after breast conserving surgery. However, the degree of benefit depends on various factors, including the aggressiveness of the cancer and the age of patient. This has led to the idea that, for some women, radiation therapy may be unnecessary.

To explore this idea, PM Senior Scientist and Clinician Dr. Fei-Fei Liu and Clinician Researcher Dr. Anthony Fyles analysed breast cancer samples from women on hormone therapy (tamoxifen). Half of these women were treated with radiation therapy, while the other half received no radiation. Molecular analyses were then conducted on their breast cancer samples to categorize them into four major breast cancer subtypes. The results revealed that women with the least aggressive subtype — known as luminal A breast cancer— benefitted the least from radiation therapy.

When the researchers only considered women over age 60 with luminal A subtype, they found that radiation therapy showed no benefit. For these women, only 1.3% experienced a recurrence without radiation therapy versus 5.0% when radiation therapy was administered.

These findings have led to the launch of a new clinical trial, sponsored by the Ontario Clinical Oncology Group, that will enroll 500 participants across Canada over three years. Dr. Fyles comments, "These results could lead to changes in clinical practice that would help minimize unnecessary treatment and side effects in up to a quarter of all women with breast cancer, and save as much as $3 million dollars annually for the province of Ontario. Post-menopausal women aged 55 or older with small node negative breast cancer who are interested in participating in the new trial should ask their treating physician if they are eligible for this study."

Supported by the Canadian Institutes of Health Research, the Giovanni And Concetta Guglietti Family Foundation, The Princess Margaret Cancer Foundation, the Campbell Family Institute for Cancer Research, and the Ontario Ministry of Health and Long-Term Care.

Identification of a Low-Risk luminal A breast cancer cohort that may not benefit from breast radiotherapy. Liu FF, Shi W, Done SJ, Miller N, Pintilie M, Voduc D, Nielsen TO, Nofech-Mozes S, Chang MC, Whelan TJ, Weir LM, Olivotto IA, McCready DR, Fyles AW. Journal of Clinical Oncology. 2015 May 11. [Pubmed abstract]

UHN researchers find a way to produce functional cartilage tissue using a method that begins with stem cells

A key feature of osteoarthritis (the most common form of arthritis) is the breakdown of articular cartilage in hand, knee and leg joints.

A study by PM Senior Scientist and McEwen Centre Director Dr. Gordon Keller has demonstrated a new method to produce cells, known as chondrocytes, that are capable of making cartilage.

While other studies have described the successful differentiation of stem cells into certain types of chondrocytes, Dr. Keller's study is the first to reveal the molecular pathways required to generate chondrocytes that can make the type of cartilage found in joints (known as articular cartilage) in a laboratory dish.

The results, published in Nature Biotechnology, showed that a particular molecular pathway, known as the TGFß signalling pathway, is involved in the process to create chondrocytes. The resulting chondrocytes were able to generate and maintain the cartilage in an experimental model for up to 12 weeks.

"This is an exciting and encouraging first step towards producing functional tissue for joint repair," says Dr. Keller. "Working with our partners at Mount Sinai Hospital, the Arthritis Program at Toronto Western Hospital and the University of Guelph, we are proceeding to transplant the stem cell-derived tissue into laboratory models to test its ability to repair damaged cartilage."

You can watch Dr. Keller discuss the possible implications of this work on a recent CTV News interview by clicking here.

This work was supported by Rob and Cheryl McEwen, the McEwen Centre for Regenerative Medicine, the Canadian Institutes of Health Research, the Krembil Foundation, Michael and Yetta Bregman in collaboration with the Campaign to Cure Arthritis, the Toronto General & Western Hospital Foundation, and The Princess Margaret Cancer Foundation. G Keller holds a Tier I Canada Research Chair in Embryonic Stem Cell Biology. Image courtesy of Stock Up.

Generation of articular chondrocytes from human pluripotent stem cells. Craft AM, Rockel JS, Nartiss Y, Kandel RA, Alman BA, Keller GM. Nature Biotechnology. 2015 May 11. [Pubmed abstract]

New WHO classification system for lung cancer used by researchers to identify people that may benefit from chemotherapy

Adenocarcinomas are cancers that can form in mucus-secreting glands. In the lung, these account for 40% of all lung cancers.

Lung adenocarcinoma is the most common form of lung cancer in Canada. Early forms of this cancer can be treated with surgery. Several clinical trials have shown that, in some patients, post-operative chemotherapy increases the likelihood of curing the cancer; however, researchers are unable to identify which patients would benefit from the more intense treatment plan.

The World Health Organization (WHO) has recently published a new classification system that categorizes lung adenocarcinoma into one of five subtypes, based on the appearance of the cancerous tissue viewed under a microscope. Using this system, an international team lead by PM Lung Pathologist and Senior Scientist Dr. Ming-Sound Tsao has shown that patients diagnosed with one of two subtypes of lung adenocarcinoma may live longer if they receive chemotherapy after their cancer is surgically removed.

The research team collected cancerous lung tissues that had been surgically removed from 575 patients who participated in lung cancer clinical trials. They examined the tissues under a microscope and classified each patient's cancer as one of the five subtypes. They determined that two subtypes, known as 'micropapillary' and 'solid', were the most aggressive and were associated with poorer survival rates. Importantly, the team found that surgery followed by chemotherapy improved cancer survival rates for patients with these two subtypes.

"Although these findings need to be further validated in prospective clinical trials, they could help doctors prescribe better treatments to each patient and improve their chance of being cured," says Dr. Tsao.

This work was supported by la Ligue contre le cancer (France), le Programme National d'Excellence Spécialisé Cancer du Poumon de l'Institut National du Cancer (France), the National Cancer Institute (USA), the Canadian Cancer Society, Sanofi, the Goustave Roussy Foundation, the European Union's Seventh Framework Programme for Research and The Princess Margaret Cancer Foundation.

Subtype classification of lung adenocarcinoma predicts benefit from adjuvant chemotherapy in patients undergoing complete resection. Tsao MS, Marguet S, Le Teuff G, Lantuejoul S, Shepherd FA, Seymour L, Kratzke R, Graziano SL, Popper HH, Rosell R, Douillard JY, Le-Chevalier T, Pignon JP, Soria JC, Brambilla EM. Journal of Clinical Oncology. 2015 Apr 27. [Pubmed abstract]