War on cancer
The "war on cancer" is the effort to find a cure for cancer by increased research to improve the understanding of cancer biology and the development of more effective cancer treatments, such as targeted drug therapies. The aim of such efforts is to eradicate cancer as a major cause of death. The signing of the National Cancer Act of 1971 by United States president Richard Nixon is generally viewed as the beginning of this effort, though it was not described as a "war" in the legislation itself.[1]
Despite significant progress in the treatment of certain forms of cancer (such as childhood leukemia[2]), cancer in general remains a major cause of death half a century after this war on cancer began,[3] leading to a perceived lack of progress[4][5][6] and to new legislation aimed at augmenting the original National Cancer Act of 1971.[7]
New research directions, in part based on the results of the Human Genome Project, hold promise for a better understanding of the genetic factors underlying cancer, and the development of new diagnostics, therapies, preventive measures, and early detection ability. However, targeting cancer proteins can be difficult, as a protein can be undruggable.
Progress[edit]
Though there has been significant progress in the understanding of cancer biology, risk factors, treatments, and prognosis of some types of cancer (such as childhood leukemia[2]) since the inception of the National Cancer Act of 1971, progress in reducing the overall cancer mortality rate has been disappointing.[5][32] Many types of cancer remain largely incurable (such as pancreatic cancer[45])
and the overall death rate from cancer has not decreased appreciably since the 1970s.[46]
The death rate for cancer in the U.S., adjusted for population size and age, dropped only 5 percent from 1950 to 2005.[3] As of 2012, WHO reported 8.2 million annual deaths from cancer[47]
Heart disease (including both Ischaemic and hypertensive) accounted for 8.5 million annual deaths. Stroke accounted for 6.7 million annual deaths.
[48]
There is evidence for progress in reducing cancer mortality.[49] Age-specific analysis of cancer mortality rates has had progress in reducing cancer mortality in the United States since 1955. An August 2009 study found that age-specific cancer mortality rates have been steadily declining since the early 1950s for individuals born since 1925, with the youngest age groups experiencing the steepest decline in mortality rate at 25.9 percent per decade, and the oldest age groups experiencing a 6.8 percent per decade decline.[50]
Dr. Eric Kort, the lead author of this study, claims that public reports often focus on cancer incidence rates and underappreciate the progress that has been achieved in reduced cancer mortality rates.[51]
The effectiveness and expansion of available therapies has seen significant improvements since the 1970s. For example, lumpectomy replaced more invasive mastectomy surgery for the treatment of breast cancer.[52]
Treatment of childhood leukemia[2] and chronic myeloid leukemia (CML) have undergone major advances since the war on cancer began. The drug Gleevec now cures most CML patients, compared to previous therapy with interferon, which extended life for approximately 1 year in only 20-30 percent of patients.[53]
Dr. Steven Rosenberg, chief of surgery at the NCI has said that as of the year 2000, 50% of all diagnosed cases of cancer are curable
through a combination of surgery, radiation, and chemotherapy.[52][54] Cancer surveillance experts have reported a 15.8 percent decrease in the age-standardized death rate from all cancers combined between 1991 and 2006 along with an approximately 1 percent annual decrease in the rate of new diagnoses between 1999 and 2006.[49] A large portion of this decreased mortality for men was attributable to smoking cessation efforts in the United States.
A 2010 report from the American Cancer Society found that death rates for all cancers combined decreased 1.3% per year from 2001 to 2006 in males and 0.5% per year from 1998 to 2006 in females, largely due to decreases in the 3 major cancer sites in men (lung, prostate, and colorectum) and 2 major cancer sites in women (breast and colorectum). Cancer death rates between 1990 and 2006 for all races combined decreased by 21.0% among men and by 12.3% among women. This reduction in the overall cancer death rates translates to the avoidance of approximately 767,000 deaths from cancer over the 16-year period. Despite these reductions, the report noted, cancer still accounts for more deaths than heart disease in persons younger than 85 years.[55][56]
An improvement in the number of cancer survivors living in the U.S. was indicated in a 2011 report by the CDC and the NCI, which noted that the number of cancer survivors in 2007 (11.7 million) increased by 19% from 2001 (9.8 million survivors). The number of cancer survivors in 1971 was 3 million. Breast, prostate, and colorectal cancers were the most common types of cancer among survivors, accounting for 51% of diagnoses. As of January 1, 2007, an estimated 64.8% of cancer survivors had lived ≥5 years after their diagnosis of cancer, and 59.5% of survivors were aged ≥65 years.[57][58] A continued decline in cancer rates in the U.S. among both women and men, across most major racial groups, and in the most common cancer sites (lung, colon and rectum), was indicated in a 2013 report by the National Cancer Institute. However, the same report indicated an increase from 2000 to 2009 in cancers of the liver, pancreas and uterus.[59]
A multitude of factors have been cited as impeding progress in finding a cure for cancer[5][6] and key areas have been identified and suggested as important to accelerate progress in cancer research.[60] Since there are many different forms of cancer with distinct causes, each form requires different treatment approaches. However, this research could still lead to therapies and cures for many forms of cancer. Some of the factors that have posed challenges for the development of preventive measures and anti-cancer drugs and therapies include the following:
Modern cancer research[edit]
Genome-based cancer research projects[edit]
The rise of a new class of molecular technologies developed during the Human Genome Project opens up new ways to study cancer and holds the promise for the discovery of new aspects of cancer biology that could eventually lead to novel, more effective diagnostics and therapies for cancer patients.[75]
[76]
[77]
These new technologies are capable of screening many biomolecules and genetic variations such as SNPs[78]
and copy number variations in a single experiment and are employed within functional genomics and personalized medicine studies.
Speaking on the occasion of the announcement of $1 billion in new funding for genome-based cancer research, Dr. Francis Collins, director of the NIH claimed, "We are about to see a quantum leap in our understanding of cancer."[34] Harold Varmus, after his appointment to be the director of the NCI, said we are in a "golden era for cancer research", poised to profit from advances in our understanding of the cancer genome.[20]
High-throughput DNA sequencing has been used to study the whole genome sequence of two different cancer tissues: a small-cell lung cancer metastasis and a malignant melanoma cell line.[79]
The sequence information provides a comprehensive catalog of approximately 90% of the somatic mutations in the cancerous tissue, providing a more detailed molecular and genetic understanding of cancer biology than was previously possible, and offering hope for the development of new therapeutic strategies gleaned from these insights.[80][81]
Modern cancer treatment[edit]
Cancer clinical trials[edit]
Researchers are considering ways to improve the efficiency, cost-effectiveness, and overall success rate of cancer clinical trials.[86]
Increased participation in rigorously designed clinical trials would increase the pace of research. Currently, about 3% of people with cancer participate in clinical trials; more than half of them are patients for whom no other options are left, patients who are participating in "exploratory" trials designed to burnish the researchers' résumés or promote a drug rather than to produce meaningful information, or in trials that will not enroll enough patients to produce a statistically significant result.
Targeted tumor treatment[edit]
A major challenge in cancer treatment is to find better ways to specifically target tumors with drugs and chemotherapeutic agents in order to provide a more effective, localized dose and to minimize exposure of healthy tissue in other parts of the body to the potentially adverse effects of the treatments. The accessibility of different tissues and organs to anti-tumor drugs contributes to this challenge. For example, the blood–brain barrier blocks many drugs that may otherwise be effective against brain tumors. In November 2009, a new, experimental therapeutic approach for treating glioblastoma was published in which the anti-tumor drug Avastin was delivered to the tumor site within the brain through the use of microcatheters, along with mannitol to temporarily open the blood–brain barrier permitting delivery of the chemotherapy into the brain.[87][88]
Public education and support[edit]
An important aspect to the war on cancer is improving public access to educational and supportive resources, to provide individuals with the latest information about cancer prevention and treatment, as well as access to support communities. Resources have been created by governmental and other organizations to provide support for cancer patients, their families and caregivers, to help them share information and find advice to guide decision making.[89][90][91][92][93][94][95]