It’s easy to feel ‘fundraiser fatigue,’ whether you’re the one being asked for money or the one doing the asking. But it is worth it. At Best Health, one of the events we raise funds for is the Weekend to End Women’s Cancers, a 60K walk organized in cities across Canada. To understand how these and other events help, we talked to one of the world’s leading experts on women’s cancers, Dr. Tak W. Mak. He’s at the Campbell Family Cancer Research Institute at Princess Margaret Hospital in Toronto, a beneficiary of the walk.
What causes cancer?
Changes to a cell’s genetic blueprint, or DNA. This can cause a cell to run wild and divide uncontrollably. The growth of these mutated cells creates one or more masses that spread and disrupt normal body functions so that the patient sickens and, if not treated in time, dies.
Cells constantly divide within the human body. When a cell divides, it has to make a complete, accurate copy of its DNA to equip the new cell. However, the genetic blueprint is made up of three billion pairs of chemical building blocks that must come together in the correct sequence. If the cell makes a mistake, a mutation is introduced into the genetic code. If mutations accumulate, the cell can become cancerous.
How do environmental and lifestyle factors play a role?
Although some cancers have a hereditary component, most do not. Any woman’s chances of developing cancer can be affected by environmental and/or lifestyle factors. For example, breast cancer incidence in Asian women is lower than in North American women. But when Asian women immigrate to Canada or the U.S., their incidence of breast cancer rises. The major lifestyle culprits are believed to be poor diet (too much fat; not enough fruit and vegetables), smoking, excessive alcohol consumption and lack of exercise. Scientists believe these factors can increase a cell’s chances of sustaining one or more DNA mutations. And exposure to environmental toxins has been linked to tumour formation.
What progress has there been in fighting women’s cancers?
Significant progress. In 1970, for every 100 women diagnosed with breast cancer, only 50 would still be living five years later. In 2010, we are much better at diagnosing breast cancers early and treating them more effectively with surgery, radiation and chemotherapy. Of every 100 women diagnosed today, 90 are still living five years later. There has been an impressive 15 percent decrease in breast cancer death rates just in the past 15 years. For cervical cancer, incidence and mortality have dropped by 40 percent over the past 40 years. These gains are due to substantial financial and intellectual resources applied not only to prevention and treatment but to basic research.
The news isn’t all good. In Western societies, breast cancer is the most common malignancy in women and the most common cause of death for women age 45 to 55. Ovarian cancer is also fairly prevalent, and although it’s only the seventh most common of all cancers affecting Canadian women, it ranks fifth in lethality.
Help us to understand the types of breast cancers.
As recently as the 1990s, all breast cancer patients received surgery in the form of a mastectomy or lumpectomy, as well as a fairly standard course of radiation and/or chemotherapy. We now know that not all breast cancers are created equal. I’ll use the analogy of a bowl of fruit. Doctors used to treat the whole bowl, assuming all its fruit was the same’say, bad apples. We didn’t know there were also bad oranges, bad grapes, bad plums, etc. By analyzing the molecular signatures of breast tumours, these cancers have been broadly classified into three types: luminal breast cancers (60 percent of all breast cancers), Her2-positive breast cancers (25 percent), and basal breast cancers (15 percent). These are very different in their DNA mutations and thus differ in their growth patterns and lethality. This distinction has led to differences in treatment as well.
What treatments are now available?
The new treatments have their roots in the 1970s, when researchers noticed that many breast cancers were driven to grow by the binding of estrogen. This discovery led to today’s drugs, which are designed to exploit this dependence. Now, after a patient has finished chemotherapy, she may be treated with an estrogen-blocking drug such as tamoxifen or an aromatase inhibitor. These block the breast cancer cells from receiving the ‘grow’ signals estrogen delivers. Since cells making up luminal breast cancers often have estrogen receptors, this line of attack is beneficial for these patients.
However, the cells making up Her2-positive and basal breast cancers often do not have estrogen receptors, making these drugs less effective for these patients. So if we look at the success of breast cancer treatment divided up by type of ‘fruit,’ we see that women with luminal breast cancers have a much greater chance of still being alive five years after treatment (and beyond) than do women with Her2-positive or basal types.
We need a ‘sharpshooter’ approach, so that we can hunt down and destroy each really bad apple or orange. I’m happy to tell you that recent research by our lab and many others worldwide is getting us closer to achieving this. One example is Herceptin.
Tell us more about this drug.
In 1985, Dr. Dennis Slamon in California started to follow a hunch that led to Herceptin’s development. It combats Her2-positive breast cancers because these malignant cells have an overload of Her2 receptors on their surfaces. The receptors bind to molecules surrounding the tumour cell and send excessive growth signals. Herceptin blocks the receptors, reducing the cell’s capacity to divide.
In the past decade, more than half a million patients have been treated with Herceptin. The proportion of those with Her2-positive cancers who survive for five years after treatment has doubled: Thousands of women have been saved. It’s an example of the good that can come out of a well-funded, collaborative R&D effort that doesn’t have to cut corners or abandon an innovative but expensive approach. By the time Herceptin hit the market in 1999, over $1 billion and 20 years of effort had been spent on basic research, pre-clinical research and clinical trials designed to ensure the drug was effective and safe. This brings home how important fundraisers like the Weekend to End Women’s Cancers are.
What other hurdles exist?
Basal breast cancers are probably the most rotten fruit in the bowl. They don’t have the receptors that would make them vulnerable to estrogen-blocking drugs or Herceptin, so the search is on for a treatment to stop them.
Another big challenge is early diagnosis. If a breast cancer is found before spreading, treatment works 90 percent of the time. But only 60 to 70 percent of breast cancers are diagnosed before spreading. Due to changes that occur in breast structure with age, mammography has been helpful in screening programs for women who are over the age of 50. Now we need to do more to improve early detection
in younger women.
What about cervical cancer?
The 40 percent drop in incidence can be attributed to preventive measures like increased condom use and hysterectomy, and the 40 percent drop in mortality is thanks to early detection (e.g., the Pap smear). Both incidence and mortality should drop even further due to the creation of the HPV vaccine.
And ovarian cancer?
There is progress, though the news is not as good. Despite intensive research, current therapies have resulted in only a 10 percent drop in lethality in the past 30 years. It can develop with no obvious symptoms and tends to be diagnosed only when advanced. There is no equivalent to mammography nor an effective screening program. A cell surface protein called CA-125 is sometimes touted as an indicator of ovarian cancer, but it is also present in many healthy people. So a large-scale screening program would have a high rate of false positives. It’s uneconomical, and results would be needlessly stressful for many patients.
One encouraging new finding is that the genetic ‘signature’ of basal breast cancers is similar to that of many ovarian cancers. If we can identify the common elements, we may be able to develop drugs to treat both of these ruthless malignancies.
What’s the mood among researchers?
Very hopeful. Researchers are embarking on a new era of discovery, and hopefully will soon uncover more drugs that can sharpshoot all types of breast and ovarian cancer cells. Many promising candidates are in clinical trials.
Of course, in a utopian world, cancers would never arise in the first place. Your readers should know that the Princess Margaret Hospital in Toronto, which houses the Campbell Family Institute, is one of the premier facilities in the world for research on and treatment of women’s cancers. Scores of specialists are trying to find out how best to prevent a cancer from starting; others are working on ways to boot our body’s immune system into overdrive so it can kill cancer cells before they multiply. Others are looking at molecules in fruit and vegetables to identify those with cancer-fighting properties; still others are focusing on survivor programs to bolster the spirit and the body. These professionals are in constant contact with experts worldwide; the amount of new knowledge generated daily is incredible.
This all requires financial support, which is why money donated at the wonderful fundraising events people have devised to increase the profile of our cause is crucial. On behalf of my fellow researchers and medical professionals, I thank the public for its generous and unwavering support.
I have faith in the power of human creativity to conquer disease, and I truly believe that we are making steady progress, winning one battle at a time. It will be a combination of prodigious research and human ingenuity, compassion and generosity that will get the job done. And then we, our children and their children will savour the sweet taste of more gentle fruits, free forever from the rotten ones.
This article was originally titled "Yes, Fundraisers for Cancer Do Help," in the September 2010 issue of Best Health. Subscribe today to get the full Best Health experience’and never miss an issue!’and make sure to check out what’s new in the latest issue of Best Health.