The Hallmarks of Cancer

Cancer develops when normal cells are transformed, then grow in an uncontrolled manner. These cells can evolve, so the genetic code (DNA) and biochemistry are changed and cells grow and do not die. Cancer cells may invade normal tissues, and eventually overcome organs, leading to decline and death.

In the fifty years since President Nixon declared his “War on Cancer,” cell biologists have found a bewildering array of biochemical processes linked to the mechanisms governing the growth of cells and tissues. Cancer is the uncontrolled proliferation of cells resulting from breakdown of these control mechanisms.

Cancer biology may seem impossibly complex; however, during the early 2000s two cancer researchers, Dr. Douglas Hanahan (University of California at San Francisco) and Dr. Robert Weinberg (Massachusetts Institute of Technology) made the science more comprehensible by categorizing each of the mechanisms into a framework called the “Hallmarks of Cancer.” In a highly cited article in the journal Cell, they described how and why hijacking of biolochemical machinery results in cancer.

Hallmarks of Cancer

A cancer cell must be able to:

1. Sustain its own growth signals;
2. Evade signals to suppress growth;
3. Resist its own scheduled death;
4. Become immortalized and continue to replicate;
5. Obtain a blood supply to nourish the growing tumour (“angiogenesis”);
6. Invade other tissues and metastasize throughout the body;
7. Reprogram metabolism so energy is from glycolysis (the cell will continue to grow in a lower oxygen environment); and
8. Evade immune destruction.

In addition to these eight hallmarks, two “enabling characteristics” are:

9. Genomic instability and mutation, which generate the genetic diversity that expedites the acquisition of the hallmarks; and
10. Inflammation, that promotes tumours and underlies several of the other hallmarks.

Finally, cancer cells create their own tumour microenvironment by recruiting and co-opting normal cells in the surrounding tissue.

Building on this vision, Michael Gilbertson and Leroy Lowe launched “Getting to Know Cancer” in Halifax in 2013, which was embraced by hundreds of prominent scientists around the globe. With extraordinary scientific leadership and wisdom, Lowe and Gilbertson and over 300 other scientists set about reframing contributors to cancer, using concrete examples of everyday exposures.

In 2015, the Halifax Project published two seminal series of peer-reviewed research papers by 350 researchers from 31 countries:

• Assessing the Carcinogenic Potential of Low-Dose Exposures to Chemical Mixtures in the Environment: The Challenge Ahead ⁵
• A Broad-Spectrum Integrative Design for Cancer Prevention and Therapy 6

In brief, by the time the average person prepares for the day and is on their way to work, the combination of exposures can add up to a complete carcinogen, checking most if not all Hallmarks.

Some of the Hallmarks also lead to birth defects and chronic disease. The costs to society range from lifelong adversity and early death, incalculable costs to families, friends and colleagues, and billions of dollars annually for health care and support.

The integrative design for cancer prevention work illustrates how chosen wisely, everyday foods and substances are beneficial, and potentially prevent cancer.

The Halifax Project makes clear that cancer prevention will not be achieved with today’s narrow, single-chemical regulatory approaches that require proof-of-harm before restrictions. Cancer prevention hinges on least-toxic approaches and best practices in all endeavours.

Michael Gilbertson and Leroy Lowe received the Group Cancer Prevention Award – 2015.