Public and Patient Information
- HOW COMMON IS CANCER?
- WHICH TYPES OF CANCER ARE MOST COMMON?
- WHO GETS CANCER?
- HOW MANY PEOPLE CURRENTLY HAVE CANCER?
- HOW CAN I FIND OUT MORE ABOUT A PARTICULAR CANCER?
- HOW DOES CANCER COMPARE TO OTHER CAUSES OF DEATH IN CALIFORNIA SUCH AS HEART DISEASE?
- HOW CAN I ENROLL IN A CLINICAL TRIAL FOR CANCER PREVENTION OR TREATMENT?
- SEVERAL PEOPLE IN MY NEIGHBORHOOD HAVE BEEN DIAGNOSED WITH CANCER. IS THIS UNUSUAL?
- WHAT IS A TRUE CANCER "CLUSTER"?
- WHAT ARE SOME COMMON MISCONCEPTIONS ABOUT TRUE CANCER CLUSTERS?
- WHY ARE CANCER RATES HIGHER IN SOME AREAS THAN OTHERS?
- WHAT DOES IT MEAN WHEN THERE IS A "STATISTICALLY SIGNIFICANT" ELEVATION OF CANCERS IN AN AREA?
- HOW DO INDIVIDUAL CHARACTERISTICS AND BEHAVIORS AFFECT CANCER RATES IN MY NEIGHBORHOOD?
- HOW CAN SO MANY CANCER CASES IN MY NEIGHBORHOOD BE DUE TO CHANCE?
- DOES THE ENVIRONMENT CAUSE CANCER?
- WHY HAVE INVESTIGATIONS OF TRUE CANCER CLUSTERS NOT BEEN
- USEFUL IN IDENTIFYING ENVIRONMENTAL CAUSES OF CANCERS?
- IF THERE ARE A LOT OF PETS IN MY NEIGHBORHOOD WITH CANCER DOES IT MEAN THERE IS A PROBLEM WITH THE ENVIRONMENT?
General Cancer Overview:
In California, more than 140,000 people will be diagnosed this year with some form of cancer, not including the common skin cancers. This is equivalent to more than 16 new cases every hour of every day. Despite the fact that cancer incidence and mortality rates are declining, it is estimated that nearly one out of every two Californians born today will develop cancer at some point in their lives, and it is likely that one in five will die of the disease.
There are many different kinds of cancer depending on where in the body the cancer starts and the type of cell involved. The most common types for males are prostate, lung, colorectal, urinary bladder and melanoma cancers. The most common types for females are breast, lung, colorectal, uterus and thyroid cancers.
Unfortunately, cancer can strike at any age, even among children and young adults. However, over 50 percent of the cancers diagnosed in California are among people 65 and older, who make up only about 11 percent of the population. Surprisingly, there are large differences among people of different ethnic origin. African-American men have the highest cancer risk, and non-Hispanic whites have substantially higher cancer rates than persons of Latino or Asian origin. Children have few differences in their cancer rates regardless of their ethnic origin. Many cancers can be cured if detected and treated promptly, and many others can be prevented by lifestyle changes, including avoidance of tobacco, consuming a healthy diet and being physically active.
The current estimate in the recent California Cancer Facts and Figures is that more than 1,277,200 Californians who are alive today have a history of cancer, not including basal or squamous cell carcinomas of the skin or certain non- invasive cancerous conditions of the uterine cervix. Many of these individuals have no further evidence of the disease, and have the same life expectancy as people who have never been diagnosed with cancer.
The National Cancer Institute's Cancer Information Service at 1-800-4-CANCER ( 1-800-422-6237), and voluntary organizations such as the American Cancer Society (1-800-ACS-2345) (or the ACS office in your area) provide information on cancers. The Centers for Disease Control and Prevention is also an excellent resource for information on cancer (http://www.cdc.gov/cancer/).
The California Department of Public Health has a number of programs that focus on cancer prevention, control, screening and/or treatment including the California Obesity Prevention Program, The Network for a Healthy California, the California Tobacco Control Program, Every Woman Counts Program (breast and cervical cancer screening and diagnostic services), the Prostate Cancer Treatment Program, the California Colon Cancer Control Program, and the Comprehensive Cancer Control Program (www.cdph.ca.gov).http://www.cancer.gov/clinicaltrials.
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What Data Does the CCR Collect?
The CCR collects demographic, diagnostic, and treatment information on individual cancer cases directly from cancer patient’s medical records. The CCR does not interview patients.
This data is used to:
- Monitor the number of new cancer cases and cancer deaths over time.
- Examine disparities in cancer risk, treatment, and survival.
- Examine treatment choices and other predictors of survival.
- Measure the success of cancer screening programs.
- Respond to public concerns and questions about cancer.
- Conduct research to find the causes and cures of cancer.
The CCR and regional registries use the data to write summary reports that inform the public, local health workers, educators, and legislators about the status of cancer.
These summary reports do NOT contain any information on individual cancer cases. The data in these reports are combined into groups for analysis.
Researchers may examine these data to identify areas that have high cancer rates, and areas where people might benefit from cancer screening and education programs.
Researchers can also use these data to look at trends in cancer diagnoses.
Opportunities to Participate in Cancer Research
Some studies require that researchers obtain additional information from individual cancer patients.
The CCR and regional registries are permitted to release patient contact information to qualified researchers. These researchers may contact patients to find out if they want to participate in a research study.
The same state law that mandates that all cancers diagnosed in California be reported to the California Department of Public Health, which operates the CCR, also requires that cancer registry data only be released for research into the causes and cures for cancer. The law mandates that patient identity be kept confidential, but also that confidential information may be released for such research.
The physician and/or hospital where a cancer patient was diagnosed should have provided a pamphlet or other document for their review regarding the cancer reporting law and notifying them that researchers may contact them.
The CCR takes the protection of a patient’s confidential health information very seriously.
The CCR will only release information to qualified researchers under tightly controlled circumstances where the research has first been approved by the California Committee for the Protection of Human Subjects (CPHS).
Patients have the right to refuse to participate in any research study without jeopardizing their current or future medical care.
Patient rights are monitored and protected by a federally approved Institutional Review Board (IRB) at the researcher’s institution. Patients are encouraged to report any concerns or complaints to the IRB. Information about how to contact the IRB should be included in the initial contact letter from the researcher.
Cancer patients may request that their contact information be withheld from researchers by contacting the CCR at the number at the bottom of this webpage.
- It offers an opportunity to join the fight against cancer.
- Thanks to the participation of many cancer patients, their families, and people without cancer, hundreds of research studies have been conducted using CCR data.
- This research has contributed to the discovery of major risk factors for cancer, improved treatment, and better survival for cancer patients in California and across the United States.
Researchers have used the CCR data to:
- Analyze geographic, racial/ethnic, and occupational differences in cancer risk;
- Evaluate the quality of medical care received by cancer patients; and
- Examine patient survival with respect to cancer type, extent of the disease, demographic characteristics, and other important factors.
California Cancer Registry (CCR) records can only be released to those who are legally authorized to obtain a patient’s confidential information (i.e., self, surviving spouse, conservator, etc.) The CCR requires all patient record requests be made in writing. The application and check list are available on the CCR website:
The state mandates that all cancers diagnosed in California be reported to the California Department of Public Health for the California Cancer Registry (CCR). The CCR does not provide for removal of cancer patient information from the registry. To fulfill its purpose of providing information to find the causes and cures for cancer, it is vital for the CCR records to be complete.
The law mandates that CCR data only be released for research into the causes and cures for cancer. The law mandates that patient identity be kept confidential, but also that confidential information may be released for such research.
However, patients can refuse to participate in any particular research study or all research studies. Cancer patients may request that their contact information be withheld from researchers by contacting the CCR at the number at the bottom of this webpage.
If you have any questions or concerns about these patient-related topics, please feel free to contact the CCR at 916-731-2500 or email us at email@example.com.
Community Cancer Concerns:
- Cancers are very common. In California, about 51% of all men and 45% of all women will develop a cancer sometime during their lives*. Therefore, you will find people who have been diagnosed with a cancer in just about every neighborhood in the state. Cancers are most common in neighborhoods with lots of older residents because cancer risk increases with age.
- All cancers are not the same. There are many types of cancers. While all cancers involve out-of-control growth of cells, each type of cancer has different risk factors, causes, treatments and outcomes. So for example, if your neighborhood has three people with three different cancers (such as lung cancer, breast cancer, and liver cancer), those three people actually have three very different and distinct conditions - even though they all are called "cancer". These three types of cancer have very different causes, so there would be no reason to think that one common factor in the neighborhood would be to blame.
- Cancer rates often vary from year to year and from place to place by chance. The number of cancer cases will never be exactly the same in each neighborhood. In some places the number will be higher than average and some places it will be lower than average for no reason other than chance. Your neighborhood could just happen to have a higher than average number of people with new cancers just by chance.
- People diagnosed with cancer are living longer. Currently, over half of all persons diagnosed with a cancer will be alive for five years or more after their diagnosis. Therefore, the chances are better than ever that there are a number of cancer survivors living in your neighborhood.
* Reference: California Cancer Registry, Annual Statistical Tables by Site (1988-2009)
Public health officials and researchers who respond to questions about clusters from the public (also referred to as community cancer concerns) think of "clusters" in two distinct ways. The first is a suspected cluster (a concern has been reported but not yet evaluated). The second is a confirmed or true cluster (where officials have confirmed that the number of cases is in fact higher than expected). Public health officials nationwide receive hundreds of inquiries every year about suspected clusters. However, after an evaluation, only a small fraction of these suspected clusters are actually confirmed as true cancer “clusters”
Many people assume that if a “cluster” is statistically confirmed it means there is something wrong with the neighborhood environment (such as pollution of the air, water or soil). This is not necessarily the case. Usually the reasons cancers "cluster" in residential neighborhoods have little to do with the physical environment. In most cases, cancers "cluster" in neighborhoods because residents have similar cancer risk factors (such as smoking or being older), or by chance.
- 1: Most cancers and cancer "clusters" in residential neighborhoods are caused by environmental contamination.
- False: The majority of known cancer risk factors are related to individual characteristics (such as age, race/ethnicity or genetic susceptibility) and behaviors (such as smoking, diet, physical inactivity, unsafe sex, and sun exposure). The relationship between cancers and environmental contamination in neighborhoods is much less established than most people realize. Nearly every investigation of a residential cancer "cluster" has failed to find a definite environmental cause.
- 2: A confirmed statistical excess of cancer cases in a neighborhood proves there is contamination.
- False: Statistics can only tell us whether or not the cancer rate in your neighborhood is truly unusual compared to other times and places. They cannot tell us the reason why rates are unusual. Other information about your neighborhood and its residents would be needed to make sense of the situation. Even unusual rates often turn out to be due to coincidence.
- 3: Neighborhood cancer concerns are investigated by testing the air, water and soil for any synthetic chemicals.
- False: Cancer concerns are investigated by determining whether or not there is actually an excess of cancer cases. In most cases, it turns out that there is not. If a statistically significant excess is found, the state and/or local health departments review the situation to determine if any further action is needed.
- 4: Causes of cancers are well understood by scientists and doctors.
- False: Although scientists have learned a great deal about the complex nature of cancers, much remains unknown. In populations, we know every year about how many cases of cancers we can expect, and can predict that cancer rates will be higher or lower in different groups of people. In individuals, however, no one can say for certain what exactly caused a cancer to develop.
- Common risk factors: If a place has many older residents, for example, cancer rates will be higher than in a place with many younger residents. Some kinds of cancers are more common among people of one race or ethnicity than another. For example, breast cancer rates are generally higher among white women than among women of other races. Therefore, we would expect breast cancer rates to be higher in areas where the population is mostly white.
- Coincidence: Cancer rates may be higher or lower in an area compared to the rest of the state just by chance.
- The environment: Cancer rates could be higher in one area than another because of something in the physical environment. However, most scientists believe that environmental factors play a much smaller role than life- style related factors (such as smoking and diet) or personal risk factors (such as age, family history or race) in the development of most cancers.
The term "statistical significance" is tricky for many people to understand. "Statistical significance" only means that the number of cases that has occurred is unusual. It does not explain why the number of cases is high. Furthermore, it does not rule out chance as a cause.
Cancer risk increases with age. Therefore, we would expect to find higher cancer rates in areas with lots of older residents.
Prostate cancer rates are higher among African-American men than among men of other races or ethnicities. Therefore, we would expect to find higher prostate cancer rates in a largely African-American neighborhood than in a largely Hispanic or Asian neighborhood.
Breast cancer rates are higher among white women than among women of other races. They also tend to be higher among women with higher socioeconomic status. Therefore, we would expect to find higher breast cancer rates in communities with many affluent white women than in other communities with a different racial and socioeconomic mix. (One reason for this difference is that women of higher socioeconomic levels more often delay child bearing and have fewer children, which in turn increases breast cancer risk.)
Residents of some communities may have similar lifestyle habits that increase risk, such as smoking, lack of physical activity or unhealthy diet. Therefore, we would expect to find higher rates of smoking-related cancers (such as lung cancers) in neighborhoods where a high proportion of residents are smokers than in neighborhoods with few smokers.
When researchers try to explain differences in cancer rates between neighborhoods, they take age, sex, and race into account.
A single neighborhood has a low probability of having high cancer rates just due to bad luck (in other words, chance). However, if you look at the entire state, you would see that lots and lots of people get cancers and there are lots and lots of neighborhoods. Therefore, there is a very good probability that some neighborhoods will have this kind of bad luck. If it happens to be your neighborhood, you naturally want to know why this has happened. Most people understandably find that "bad luck" is not a very satisfying explanation and want something --or someone --to be held responsible.
Nonetheless, most experts on cancers and cancer "clusters" believe that chance is the explanation for neighborhood cancer "clusters" far more often than most people would think. "Chance" in this situation means that there is no common reason why cancers have occurred in a particular neighborhood. Given the same set of genetic and lifestyle factors, the same people probably would have gotten cancer no matter where they lived. But sometimes several people who develop cancer just happen to live in the same area -- by chance. An investigation into the cause of a chance "cluster" will never result in an answer because none exists.
One reason for confusion about this is that the term "environment" means something different to researchers than it does to most members of the public. For researchers, the "environment" usually means any factor that is not hereditary. This may include things like cigarette smoking, diet, sunlight and infections in addition to factors in the air, soil and water. If we use this broad definition, we would say that the "environment" is a big factor in cancer risk.
However, when most members of the public think of cancer and the "environment" they are thinking of contaminants in the air, water, or soil that might cause cancers (called carcinogens). We all live in environments that contain carcinogens, and we are all exposed to a greater or lesser degree every day. The relationship between these carcinogens and cancer development is subtler, more complex and less established than most people think.
Much of what we know about these carcinogens has been learned from studies of exposures in the workplace. In the workplace, unlike in neighborhoods, chemical exposures are more often known, and occur at high levels for prolonged periods of time.
Learning more about environmental carcinogens and their role in cancer development is very important. Because their effects are complex and difficult to detect, studies of environmental carcinogens and cancer must be carefully designed and include large numbers of people. A neighborhood with a cancer "cluster" is not a very good place to study the effects of environmental carcinogens because usually the number of cases is too small, and the number of possible carcinogens is too large to be able to make a connection.
WHY HAVE INVESTIGATIONS OF TRUE CANCER CLUSTERS NOT BEEN USEFUL IN IDENTIFYING ENVIRONMENTAL CAUSES OF CANCERS?Over the years, nearly every neighborhood cancer "cluster" investigation has failed to identify any environmental cause. This is not for lack of trying, but because cancers are very complex diseases. Methods that work well to identify the cause of an infectious disease outbreak do not work well with neighborhood cancer clusters. The reasons include:
- Cancers take a long time to develop. For most cancers, the period between exposure to a carcinogen and the development of cancer may be ten to twenty years or more. By the time cancer rates have increased in an area, the carcinogen may no longer be measurable in the environment.
- People change residences. In many cases, by the time a person is diagnosed with a cancer, he or she no longer lives in the area where an exposure may have occurred. Cancer registries have no way to track where people lived before or after developing a cancer.
- Residential cancer clusters contain few cases. Even if the cancer rate in an area is found to be "statistically significant" there usually are too few cases and too many possible exposures to allow scientists to work backward to find the cause. Carcinogens that may be found in a neighborhood with several cancer cases are also likely to be found in areas without many cases.
- It is not currently possible to determine the cause of cancer in an individual. When a person gets a cancer, doctors may suspect that certain risk factors are largely to blame. However, doctors do not have any reliable way to determine the exact cause or combination of causes for the cancer. Therefore, in a neighborhood "cluster" situation, doctors cannot be certain about what caused a cancer in any individual resident.
IF THERE ARE A LOT OF PETS IN MY NEIGHBORHOOD WITH CANCER DOES IT MEAN THERE IS A PROBLEM WITH THE ENVIRONMENT?The state does not track cancers in animals. Therefore, there really is no way to tell if the number of animal cancers in any particular neighborhood is truly unusual. However, we know that cancers are common especially among older animals. This is because cancer risk increases with age, just as it does in people.
Humans and animals have different cancer risks. Cancers that are uncommon in humans may be very common among dogs, for example, and vice-versa. Cancer risks also vary between different animals, and even within breeds of the same species. There is no reason to suspect that groupings of different types of animals with different types of cancers have a common underlying cause.
In most counties, the county health department should be contacted first. These departments will usually be familiar with local issues, and you may find that officials are already aware of the area you are concerned about. County health departments may respond to community cancer concerns themselves or refer callers to the regional registry depending upon the resources available in each county.
Sometimes, further evaluation is necessary. The epidemiologist first works to identify the number of all observed cases of the cancer in the area and time period of concern. Then this observed number is compared to the number that would be expected based upon rates in other areas or other time periods, after adjusting for differences in the age, sex and race/ethnicity make-up of the populations. A statistical test is used to judge whether or not the difference between the number of cases observed and the number expected is likely to be due to normal random variation. If an excess number of cancer cases is confirmed, the situation is reviewed further by the health department to determine if any further investigation is needed.
Although this brief description may make this procedure sound simple, in fact it may require a considerable amount of registry staff time and resources, and may take several weeks to complete.
Questions and Resources
County Health Department/Regional Registry Contacts:
- Regional Cancer Registries
- County Health Department Contacts
- Check your local directory for county government
- American Cancer Society
- Occupational cancer risks and Environmental Pollutants and Cancer Risk: The American Cancer Society describes environmental risks (including smoking, diet, sun exposure, and infectious diseases, as well as chemicals and radiation in our homes and workplaces. Learn more about these risks and how you can reduce them.
- Centers for Disease Control and Prevention (CDC)
- CDC cancer information page.
- Agency for Toxic Substances and Disease Registry
- National Center for Environmental Health
- National Cancer Institute
- Cancer Clusters Fact Sheet:The National Cancer Institutes fact sheet on cancer clusters.
- Cancer Information Service: The National Cancer Institute's (NCI's) Cancer Information Service (CIS) is a national information and education network. The CIS is a free public service of the NCI, the Nation's primary agency for cancer research. The CIS can be reached at 1-800-4-CANCER.
- Cancer and the Environment: A 47 page booklet "Cancer and the environment: what you need to know, what you need to do" produced by the National Cancer Institute (NCI) and the National Institute of Environmental Health Sciences. This booklet addresses about the connection between cancer and exposure to toxic substances in the environment
- National Institute of Environmental Health Sciences
- SEER (Surveillance, Epidemiology and End Results)
- Childhood Cancers
- Environmental Protection Agency
- Office of Children's Health Protection
If you would like any additional information regarding the California Cancer Registry please contact the Webmaster at firstname.lastname@example.org or call the California Cancer Registry in Sacramento at (916) 731-2500.