May 26, 2015

Cancer: To know is to overcome

It is estimated that one of two people born today will be diagnosed with cancer in his or her lifetime.

In the United States, a quarter of all deaths are related to cancer. Despite tremendous advances in treatment, avoiding cancer altogether remains the best weapon against the disease.

Cancer is the name given to a collection of related diseases. It is a broad term used to encompass several malignant diseases.

There are over 100 different types of cancer, affecting various parts of the body. Each type of cancer is unique with its own causes, symptoms, and methods of treatment. Like with all groups of disease, some types of cancer are more common than others. The most common types of cancer in the United States based on frequency of diagnosis are: blander cancer, breast cancer and colon cancer.

In all types of cancer, some of the body’s cells begin to divide without stopping and spread into surrounding tissues.

Cancer can start almost anywhere in the human body, which is made up of trillions of cells. Normally, human cells grow and divide to form new cells as the body needs them. When cells grow old or become damaged they die and new cells take their place.

When cancer develops, however, this orderly process breaks down. As cells become more and more abnormal, old or damaged cells survive when they should die, and new cells form when they are not needed. These extra cells can divide without stopping and may form growths called tumours.

Many cancers form solid tumours, which are masses of tissue. Cancers of the blood, such as leukemia, generally do not form solid tumours.

Cancerous tumours are malignant, which means they can spread into or invade nearby tissues. In addition, as these tumours grow, some cancer cells can break off and travel to distant places in the body through the blood or the lymph system and form new tumours far from the original tumour.

Unlike malignant tumours, benign tumours do not spread into, or invade, nearby tissues. Benign tumours can sometimes be quite large, however. When removed, they usually don’t grow back, whereas malignant tumours sometimes do.

In the spring of 2014, a team of British archaeologists announced the discovery of the oldest known case of metastatic cancer in a human being, in the skeleton of a young man who died in the Nile River valley in ancient Egypt some 3,200 years ago. Scientists hope the new findings will help them better understand the origins and evolution of this all-too-common, often deadly disease.

After examining the young man’s skeleton using radiography and a scanning electron microscope, a team of researchers from Durham University and the British Museum were able to see clear images of lesions on the bones.

According to their findings, published in March 2014, in the journal PLOS ONE, the lesions suggested that a type of cancer had spread to cause tumours throughout the body, including the pelvis, spine, shoulder blades, breastbone, collarbones and ribs. According to Michaela Binder, a PhD student at Britain’s Durham University, cancer is definitely the cause of lesions. 

“Our analysis showed that the shape of the small lesions on the bones can only have been caused by a soft tissue cancer ... though the exact origin is impossible to determine through the bones alone,” Mr. Binder said.

The oldest known description and surgical treatment of cancer was discovered in the Ancient Egyptian Edwin Smith Papyrus and dates back to approximately 1600 B.C. The writing says about the disease, "There is no treatment.”

In the 16th and 17th centuries, it became more acceptable for doctors to dissect bodies to discover the cause of death.

With the widespread use of the microscope in the 18th century, it was discovered that the “cancer poison” eventually spreads from the primary tumor through the lymph nodes to other parts of the body. This view of the disease was first formulated by the English surgeon Campbell De Morgan between 1871 and 1874. The use of surgery to treat cancer had poor results due to problems with hygiene.

The modern era of cancer research really began in the 19th century and led to the current concept developed by several investigators, notably Rudolf Virchow, that cancer is a disease of cells.

The field of cancer research had begun to grow rapidly by the end of the 19th century and the beginning of the 20th.

In Europe, spontaneous tumors had been propagated in mice, and Gaylord and Tyzzer, two of the founders of the American Association for Cancer Research (AACR), soon expanded this research in America.

Use of radium and X-rays was in its infancy. American institutes for research were being established (Roswell Park, The Rockefeller Institute, and The Institute of Cancer Research at Columbia University), and private endowments to fund research were beginning to proliferate, although direct government research support was not yet available. The first congresses on cancer had just been held in Europe.

Over the last year, significant progress has been made in the treatment of both common and rare cancers, leading to longer patient survival and improved quality of life.

Advances ranged from targeted therapies - a type of treatment that uses drugs or other substances, such as monoclonal antibodies, to identify and attack specific cancer cells - for disease settings where previously no effective treatments existed, to progress in immunotherapy—an area of research that had seen little success until recent years.

In addition, the strategy of combining different types of therapy showed powerful results in two large-scale, federally funded studies; a combination of a chemotherapy drug with standard hormone therapy brought the longest survival improvement for patients with advanced prostate cancer, and adding radiotherapy to standard chemotherapy extended the lives of patients with a class of brain cancers called glioma by 5 years.

Treatments that add, block, or remove hormones to slow or stop the growth of certain cancers (such as prostate and breast cancer), synthetic hormones or other drugs may be given to block the body’s natural hormones are also showing promise. 

For some patients with certain cancers, it’s true that the prognosis is decidedly better now than four decades ago. Childhood leukemia, a virtual death sentence in the 1960s, now has an 80% survival rate; Hodgkin’s disease is all but curable, while some of the major adult cancers, like breast and prostate, can be successfully treated now, if caught early enough.

Despite advances, some scientists believe the search for cure to the world’s number-one health risk is indeed being lost, even as research costs surge well past $100-billion.

In the U.S. alone, the National Cancer Institute (NCI) — created by the Nixon administration more than 40 years ago to help fight the war — has spent close to $100-billion in funding, with hundreds of millions more raised and spent by cancer charities and hospital foundations.

The numbers in Canada are smaller, even when put on a per-capita basis, but still impressive. Total cancer-research spending Canada in 2009 was $545-million, according to the Canadian Cancer Research Alliance, with the largest contribution  ($132-million) coming from the Canadian Institutes of Health Research, Canada's counterpart to the NCI.

Though the per-capita cancer mortality has fallen, the total number of deaths continues to soar, as the rate of new cases also climbs.

Jim Watson, the Nobel-winning discoverer of DNA’s double-helix structure, caused a minor sensation by arguing that curing most metastatic cancers — cancers that spread in the body — remains more daunting than ever, while researchers pursue scientific dead ends.

Lamenting a “conservative” research establishment that he suggested is reluctant to take scientific risks, he urged scientists to follow new, unexplored, yet more promising directions.

An American Cancer Society study last year suggested that overall cancer mortality would barely have shrunk at all after the early 1990s if not for the huge societal shift away from tobacco.

Despite tremendous advances in treatment, avoiding cancer altogether remains the best weapon against the disease.

People can substantially decrease the risk of getting cancer by changing their lifestyle (exercising regularly, maintaining a healthy weight, having a balanced diet) and avoiding things known to cause cancer, such as cigarette smoking and exposure to ultraviolet light.

Growing research evidence suggests that being overweight or obese increases one’s risk of developing many types of cancer, and can also complicate treatment and worsen outcomes after a cancer diagnosis.

Obesity is quickly overtaking tobacco as the leading preventable cause of cancer.

As many as 84,000 cancer diagnoses in the US each year are attributed to obesity, and obesity or excess weight contributes to up to one in five cancer-related deaths.

If current obesity trends continue, it is estimated there could be an additional 500,000 cases of cancer by 2030.  

However, scientists are beginning to understand the biological factors underlying the association between obesity and cancer. The ultimate goal is to combine this knowledge with healthy lifestyle interventions to reduce obesity’s impact on cancer rates.

Specific drugs are already recommended to people at increased risk for certain types of cancer, such as breast and ovarian cancers. Early results from an ongoing study point to a promising new way to prevent the development of breast cancer after menopause among high-risk women.

Another important strategy for reducing cancer deaths is screening, which can find pre-cancerous conditions or cancer at an early stage, substantially increasing the chances for successful treatment and longer survival.

Several cancer screening tests are routinely performed in the North America:  mammography (for breast cancer), colonoscopy (for colon and rectal cancers), and Pap and human papillomavirus (HPV) tests (for cervical cancer).

In 2013, the US Preventive Services Task Force (USPSTF) endorsed annual low-dose CT lung cancer screening for current and former heavy smokers.

In 2014, the task force issued a formal set of recommendations regarding this screening. Additional recent research will help improve the efficacy of low-dose CT lung cancer screening and reduce potential harms by identifying the populations that stand to benefit the most from screening, and developing ways to reduce false-positive screening results.

To date the research has produced incremental - though not insignificant – advances, but a cure is not on the horizon.