Statistics and research in metastatic breast cancer

Research

Research on metastatic cancers in general is low, in fact, only 5 percent of cancer research funds are spent on metastases while it kills 90% of all cancer patients [1]. This includes 5% of research funding on all metastatic cancers in Europe and even less than that in the United States [2]. In general, treatment choices are guided by breast cancer type, location and extent of metastasis in the body, previous treatments and other factors [3].

Nonetheless, new research and treatment options are emerging for women living with metastatic breast cancer. For example, biophosphonates
are drugs that used to help strengthen and reduce the risk of fractures in bones that have been weaked by MBC [4]. Denosumab is another treatment method that works
strengthen and bones for metastasis; it is currently being studied to see if it can integrated to make adjuvant treatments more effective [5].

Perjeta

On April 13, 2013, Health Canada approves PERJETA™ a new first-in-class targeted therapy for the treatment of HER2-positive metastatic breast cancer [6]. A recent international randomized trial funded by Roche confirmed the effectiveness of the drug. The trial included over 800 women with advanced Her2+ disease,; the participants all took Herceptin (trastuzumab, an antibody) and docetaxel (a chemotherapy, usually sold as Taxotere) and, based on the randomization, also received infusions of Perjeta or a placebo. Overall survival among women who received Perjeta was extended by nearly 16 months, as compared to the control [7].

Over half of the women with Her2+ metastatic breast cancer who received all three drugs (Perjeta, Herceptin and chemotherapy) lived for over 4.5 years on the study. This result confirms and bolsters earlier results of CLEOPATRA study, published in the NEJM, which led to the FDA’s initial 2012 approval of Perjeta for use in metastatic breast cancer [8].

General Statistics

In general, about 20-30 percent of those diagnosed with breast cancer will have it metastasize. Approximately, 6-10 perecent of new breast cancer cases are initially diagnosed as Stage IV or metastatic. Furthermore, the median survival after a metastatic breast cancer diagnosis is three years, up from 18 months in 1970 [9].

A few more statistics [10]:

  • Compared to white women, African-American women are diagnosed at a higher rate under age 40 and more likely to die from
    breast cancer at every age
  • Breast cancer is the number one cause of cancer death in young women under age 50

MBC Canadian Statistics

Unfortunately, limited statistical research exists about Canadian women living with metastatic breast cancer. Based on the Canadian Cancer Society’s 2014 statistics, here’s what we do know [11]:

  • This year 93, 600 Canadian women will be diagnosed with cancer;
  • And 36, 600 women will die from cancer;
  • Breast cancer will account for about one-quarter of all new cancer cases in women
  • Breast cancer is the second most common cause of cancer death in females

Is Metastatic Breast Cancer (MBC) the same as Stage IV cancer when talking about statistics?

No. Although, stage IV cancer and MBC are used interchangeably in the media and by the public, they mean very different things in the medical and statistical world [12].
The American Cancer Society explains it:

‘A cancer’s staging does not change over time: Stage IV cancer and MBC are not the same.

An important point some people have trouble understanding is that the stage of a cancer does not change over time, even if the cancer progresses. A cancer that comes back or spreads is still referred to [in medical community] by the stage it was given when it was first found and diagnosed–information about the current extent of the cancer is added to it.

For example, let’s say a woman was first diagnosed with stage II breast cancer and the cancer went away with treatment. But then it came back with spread to the bones. The cancer is still called a stage II breast cancer, now with recurrent disease in the bones. If the breast cancer did not respond to treatment and spread to the bones it’s called a stage II breast cancer with bone metastasis.

In either case, the original stage does not change and it’s not called a stage IV breast cancer. A stage IV breast cancer refers to a cancer that has already spread to a distant part of the body when it’s first diagnosed. A person keeps the same diagnosis stage, but more information is added to the diagnosis to explain the current state of the disease.

This is important to understand because survival statistics and information on treatment by stage for specific cancer types refer to the stage when the cancer was first diagnosed [13].’

Many thanks to the Metastatic Breast Cancer Network for providing well-sourced and documented statistics.

[1] Steeg, Patricia S., and Dan Theodorescu. “Metastasis: A Therapeutic Target for Cancer.” US National Library of Medicine. National Institutes of Health, 5 Feb. 2008. Web. 8 Oct. 2014.
[2] ibid.
[3] “13 Facts Everyone Should Know about Metastatic Breast Cancer.” MBCN: Developing Awareness. Metastatic Breast Cancer Network, n.d. Web. 10 Oct. 2014.
[4] “What’s New in Breast Cancer Research and Treatment?” What’s New in Breast Cancer Research and Treatment? American Cancer Society, 25 Sept. 2014. Web. 09 Oct. 2014.
[5] ibid.
[6] Frampton, Jeanelle. “Health Canada Approves PERJETA™, a New First-in-class Targeted Therapy for the Treatment of HER2-positive Metastatic Breast Cancer.” Roche Canada. CNW NewsWire, 23 Apr. 2013. Web. 10 Oct. 2014.
[7] Schattner, Elaine. “Trial Confirms That Perjeta Extends Survival In Metastatic Breast Cancer.” Forbes. Forbes Magazine, 28 Sept. 2014. Web. 10 Oct. 2014.
[8] ibid.
[9] “Most Common Cited Statistics for MBC.” Metastatic Breast Cancer Network. Metastatic Breast Cancer Network, n.d. Web. 8 Oct. 2014.
[10] ibid.
[11] “Cancer Statistics at a Glance.” Canadian Cancer Society. Canadian Cancer Society, n.d. Web. 8 Oct. 2014.
[12] “Statistics: Stage IV vs MBC.” Metastatic Breast Cancer Network. Metastatic Breast Cancer Network, n.d. Web. 8 Oct. 2014.
[13] “Staging.” American Cancer Society. American Cancer Society, n.d. Web. 8 Oct. 2014.