The US Centers for Disease Control and Prevention (CDC) say many cancers that could be prevented from becoming
advanced are being diagnosed too late, despite available screening tests, which if implemented more widely, would catch more
cancers early enough for treatment to be effective.
These are the findings of the first nationwide report to highlight the incidence of late-stage diagnosis and screening prevalence of four cancers detectable through screening tests, that is cancers of the colon, rectum, breast and cervix.
The report, which covers 2004 to 2006, also details the findings by age, race/ethnicity, and state. It is published in the CDC's Morbidity and Mortality Weekly Report (MMWR) for 26 November.
Co-author Dr Marcus Plescia, Director, Division of Cancer Prevention and Control at the CDC, told the press that their findings are a cause for concern because:
"So many preventable cancers are not being diagnosed when treatment is most effective."
He and his co-authors found that nearly half of colorectal and cervical cancer cases, and one third of cases of breast cancer in the US are diagnosed during the later stages of the disease when treatments are far less likely to be effective.
"More work is needed to widely implement evidence-based cancer screening tests which may lead to early detection and, ultimately, an increase in the number of lives saved," said Plescia.
For national data on new cancer cases, the authors used cancer registries linked to the CDC National Program of Cancer Registries and the National Cancer Institute's Surveillance, Epidemiology, and End Results Program.
For state-level data on cancer screening they used the CDC Behavioral Risk Factor Surveillance System.
They found that differences among states in late-stage cancer diagnosis could partly be due to screening rates differing by location and by demographic group.
Late Stage Cancer Incidence Rates: By Age/EthnicityThe main highlights of the report showed that:
- Colorectal cancers: late-stage incidence increased with age and was highest among black men and women.
- Breast cancer: late-stage incidence was highest among women aged between 70 and 79 years, and among black women.
- Cervical cancer: late-stage incidence was highest among women aged 50 to 79 and among Hispanic women.
Late Stage Cancer Incidence Rates: By StateThe main highlights of the report showed that:
- Colorectal cancers: late-stage incidence rates ranged from 51.0 to 86.5 per 100,000 people per year, and were highest in Connecticut, Delaware, Illinois, Iowa, Kentucky, Louisiana, Maine, Nebraska, New Jersey, and Pennsylvania.
- Breast cancer: incidence rates ranged from 92.2 to 132.1 per 100,000 people per year, and were highest in Alabama, the District of Columbia, Kansas, Louisiana, Mississippi, New Jersey, Oklahoma, Pennsylvania, Tennessee, and Washington.
- Cervical cancer: late-stage incidence rates ranged from 3.0 to 8.3 per 100,000 people per year, and were highest in Arkansas, the District of Columbia, Illinois, Kentucky, Louisiana, Mississippi, Nevada, New Mexico, and Oklahoma.
After lung cancer, colorectal cancer is the second leading cause of cancer deaths in the US, where in 2006 more than 139,000 people discovered they had the disease and more than 53,000 died of it.
Screening for colorectal cancer looks for pre-cancerous polyps that can be removed and prevent cancer. The other advantange of screening is that it can detect cancer early, when treatment is most likely to be effective and stop the cancer spreading.
In 2006, more than 191,000 women in the US found out they had invasive breast cancer and more than 40,000 died of the disease. Men can also get breast cancer: in the US the National Cancer Institute estimates that 1,970 men will discover they have breast cancer this year and 390 will die of it.
The CDC says the best way to detect breast cancer early, that is before any lumps are big enough to feel by hand or cause symptoms, is to have a mammogram, where the breast tissue is X-rayed. Detection at this early stage also means the cancer is much easier to treat successfully.
Despite cervical cancer being the easiest gynecologic cancer to prevent with regular screening tests and follow-up, every year about 12,000 American women find out they have the disease. Screening for this cancer finds pre-cancerous lesions that can be removed before the cancer develops.
Based on research evidence, the US Preventive Services Task Force recommends the following approaches to screening for the four cancers covered in the report:
- Colorectal cancer: all people aged 50 to 75 years at average risk, should be screened either via an annual fecal occult blood test, a flexible sigmoidoscopy every five years, or a colonoscopy every 10 years.
- Breast cancer: women aged from 50 to 74 years should have a mammogram every two years.
- Cervical cancer: women should have a Pap test within three years of becoming sexually active, or turning 21 years of age, whichever is first; in addition, they should have an annual test for three years, then after that, at least once every three years, until they are 64 years of age.
They also noted that quality of follow-up of abnormal test results is also an important part of catching more cancers early.
They found that patients with low income or in certain racial or ethnic groups experience longer delays in getting their diagnosis and treatment after an abnormal test. They suggested much of this is likely to be due to differences in use and location of health care services, and not just because of lack of adequate insurance.
The authors said their findings emphasize the need for continued monitoring and surveillance of late-stage cancer diagnosis in the population.
These figures can then be used to pinpoint pockets in the population that would benefit from campaigns to get them to participante in screening and keep an eye on early detection programs.
"Multiple factors, including individual characteristics and health behaviors as well as provider and clinical systems factors, might account for why certain populations are underscreened, " they wrote.
"Surveillance of Screening-Detected Cancers (Colon and Rectum, Breast, and Cervix) --- United States, 2004- 2006."
MMWR, Surveillance Summaries, November 26, 2010 / 59(SS09);1-25
S. Jane Henley, Jessica B. King, Robert R. German, Lisa C. Richardson, Marcus Plescia, of the CDC's Division of Cancer Prevention and Control, National Center for Chronic Disease Prevention and Health Promotion.
Written by: Catharine Paddock, PhD