EPIDEMIOLOGY OF CANCER

Views:
 
     
 

Presentation Description

No description available.

Comments

Presentation Transcript

Slide 1:

Dr. Muhammedirfan H. Momin Assistant Professor Community Medicine Department Government Medical College, Surat.

What is cancer? :

What is cancer?

What is cancer? :

What is cancer? Cells in the body normally divide in a very controlled fashion. In cancer, the genetic material found in each cell is damaged for some reason, and causes the cell to lose the ability to divide in a controlled way, and the cell begins to divide uncontrollably. The abnormal cells accumulate into a tumor, and have the potential to spread cancerous cells to other organs (a process known as metastasis or spread). This metastatic process is what leads to death from cancer. The epidemiology of cancer is the study of the factors affecting cancer.

What is cancer?:

What is cancer? Cancer (medical term: malignant neoplasm ) is a class of diseases in which a group of cells display uncontrolled growth ( division beyond the normal limits), invasion (intrusion on and destruction of adjacent tissues), and sometimes metastasis (spread to other locations in the body via lymph or blood). These three malignant properties of cancers differentiate them from benign tumors , which are self-limited, and do not invade or metastasize. The branch of medicine concerned with the study, diagnosis, treatment, and prevention of cancer is oncology

Terminology:

Terminology Tumor or tumour: originally, it meant any abnormal swelling, lump or mass. In current English, however, the word tumor has become synonymous with neoplasm, specifically solid neoplasm. Neoplasm : the scientific term to describe an abnormal proliferation of genetically altered cells. Neoplasms can be benign or malignant: Malignant neoplasm or malignant tumor : synonymous with cancer . Benign neoplasm or benign tumor : a tumor (solid neoplasm) that stops growing by itself, does not invade other tissues and does not form metastases

Terminology:

Terminology Invasive tumor is another synonym of cancer . The name refers to invasion of surrounding tissues. Pre-malignancy , pre-cancer or non-invasive tumor: A neoplasm that is not invasive but has the potential to progress to cancer (become invasive) if left untreated. These lesions are, in order of increasing potential for cancer. Screening : a test done on healthy people to detect tumors before they become apparent. A mammogram is a screening test.

Terminology:

Terminology Diagnosis : the confirmation of the cancerous nature of a lump. This usually requires a biopsy or removal of the tumor by surgery , followed by examination by a pathologist . Surgical excision : the removal of a tumor by a surgeon . Surgical margins : the evaluation by a pathologist of the edges of the tissue removed by the surgeon to determine if the tumor was removed completely ("negative margins") or if tumor was left behind ("positive margins").

Terminology:

Terminology Grade : a number (usually on a scale of 3) established by a pathologist to describe the degree of resemblance of the tumor to the surrounding benign tissue. Stage : a number (usually on a scale of 4) established by the oncologist to describe the degree of invasion of the body by the tumor. Recurrence : new tumors that appear at the site of the original tumor after surgery. Metastasis : new tumors that appear far from the original tumor.

Terminology:

Terminology Chemotherapy : treatment with drugs. Radiation therapy : treatment with radiations. Adjuvant therapy: treatment, either chemotherapy or radiation therapy, given after surgery to kill the remaining cancer cells. Prognosis : the probability of cure after the therapy. It is usually expressed as a probability of survival five years after diagnosis. Alternatively, it can be expressed as the number of years when 50% of the patients are still alive.

Classification:

Classification Carcinoma : Malignant tumors derived from epithelial cells. This group represents the most common cancers, including the common forms of breast , prostate , lung and colon cancer . Sarcoma : Malignant tumors derived from connective tissue , or mesenchymal cells. Lymphoma and leukemia : Malignancies derived from hematopoietic ( blood -forming) cells Germ cell tumor : Tumors derived from totipotent cells. In adults most often found in the testicle and ovary ; in fetuses, babies, and young children most often found on the body midline, particularly at the tip of the tailbone; in horses most often found at the poll (base of the skull). Blastic tumor or blastoma : A tumor (usually malignant) which resembles an immature or embryonic tissue. Many of these tumors are most common in children.

Classification:

Classification Malignant tumors (cancers) are usually named using -carcinoma , -sarcoma or -blastoma as a suffix, with the Latin or Greek word for the organ of origin as the root. For instance, a cancer of the liver is called hepatocarcinoma ; a cancer of the fat cells is called liposarcoma . For common cancers, the English organ name is used. For instance, the most common type of breast cancer is called ductal carcinoma of the breast or mammary ductal carcinoma . Here, the adjective ductal refers to the appearance of the cancer under the microscope, resembling normal breast ducts.

Classification:

Classification Benign tumors (which are not cancers) are named using -oma as a suffix with the organ name as the root. For instance, a benign tumor of the smooth muscle of the uterus is called leiomyoma (the common name of this frequent tumor is fibroid ). Unfortunately, some cancers also use the -oma suffix, examples being melanoma and seminoma .

Problem Statement:

Problem Statement World Every year- 10 million diagnosed 6 million die Worldwide - Lung Cancer (12.3 %) Breast Cancer(10.4%) Colorectal Cancer(9.4%) Death from cancer - Lung (17.8%) Stomach (10.4%) Liver (8.8 %)

Slide 15:

Male most common (by occurrence) most common (by mortality) [12] prostate cancer (25%) lung cancer (31%) lung cancer (15%) prostate cancer (10%) colorectal cancer (10%) colorectal cancer (8%) bladder cancer (7%) pancreatic cancer (6%) non-Hodgkin lymphoma (5%) liver & intrahepatic bile duct (4%)

Slide 16:

Female most common (by occurrence) most common (by mortality) [12] breast cancer (26%) lung cancer (26%) lung cancer (14%) breast cancer (15%) colorectal cancer (10%) colorectal cancer (9%) endometrial cancer (7%) pancreatic cancer (6%) non-Hodgkin lymphoma (4%) ovarian cancer (6%)

India:

India 3.4 % of all deaths – cancer 7 lakh new cases detected every year Males - mouth/oropharynx oesophagus stomach Lower respiratory tract Females - Cervix Breast mouth/oropharynx oesophagus

:

Environmental Genetic Tobacco Alcohol Dietary Factors Occupational exposures Viruses Parasites Customs ,habits, Lifestyles Others – sunlight, pollution, drugs Eg Retinoblastoma in Children Leukemia in Mongols CAUSES OF CANCER

Smoking and Tobacco:

Smoking and Tobacco The incidence of lung cancer is highly correlated with smoking. Source:NIH. Decades of research has demonstrated the link between tobacco use and cancer in the lung, larynx, head, neck, stomach, bladder, kidney, oesophagus and pancreas. Tobacco smoke contains over fifty known carcinogens, including nitrosamines and polycyclic aromatic hydrocarbons .

Slide 23:

Tobacco is responsible for about one in three of all cancer deaths in the developed world, and about one in five worldwide. Indeed, lung cancer death rates in the United States have mirrored smoking patterns, with increases in smoking followed by dramatic increases in lung cancer death rates and, more recently, decreases in smoking followed by decreases in lung cancer death rates in men. However, the numbers of smokers worldwide is still rising, leading to what some organizations have described as the tobacco epidemic .

Mutation: chemical carcinogens:

Mutation: chemical carcinogens Cancer pathogenesis is traceable back to DNA mutations that impact cell growth and metastasis. Substances that cause DNA mutations are known as mutagens, and mutagens that cause cancers are known as carcinogens. Particular substances have been linked to specific types of cancer. Prolonged exposure to asbestos fibers is associated with mesothelioma . Many mutagens are also carcinogens , but some carcinogens are not mutagens. Alcohol is an example of a chemical carcinogen that is not a mutagen. Such chemicals may promote cancers through stimulating the rate of cell division. Faster rates of replication leaves less time for repair enzymes to repair damaged DNA during DNA replication , increasing the likelihood of a mutation.

Mutation: ionizing radiation :

Mutation: ionizing radiation Sources of ionizing radiation , such as radon gas, can cause cancer. Prolonged exposure to ultraviolet radiation from the sun can lead to melanoma and other skin malignancies. Non-ionizing radio frequency radiation from mobile phones and other similar RF sources has also been proposed as a cause of cancer, but there is currently little established evidence of such a link.

Viral or bacterial infection:

Viral or bacterial infection Some cancers can be caused by infection with pathogens , viral infection. The main viruses associated with human cancers are human papillomavirus , hepatitis B and hepatitis C virus.

Slide 27:

In addition to viruses, researchers have noted a connection between bacteria and certain cancers . The most prominent example is the link between chronic infection of the wall of the stomach with Helicobacter pylori and gastric cancer . Although only a minority of those infected with Helicobacter go on to develop cancer, since this pathogen is quite common it is probably responsible for the majority of these cancers.

Immune system dysfunction :

Immune system dysfunction HIV is associated with a number of malignancies, including Kaposi's sarcoma , non-Hodgkin's lymphoma , and HPV -associated malignancies such as anal cancer and cervical cancer . AIDS -defining illnesses have long included these diagnoses. The increased incidence of malignancies in HIV patients points to the breakdown of immune surveillance as a possible etiology of cancers

Signs and symptoms:

Signs and symptoms

Danger Signals:

Danger Signals A lump or a hard area in breast A change in wart or mole A persistent change in bowel habits A persistent cough or hoarseness Excessive loss during menstrual periods or loss of blood outside usual dates. Blood loss from any natural orifice A swelling that does not get better Unexplained loss of weight

Oral cancer:

Oral cancer 50 – 70% of all cancers diagnosed in india Risk factors Tobacco Alcohol Precancerous lesions Cultural patterns

Cancer cervix:

Cancer cervix Most common cancer of women –developing countries Causative agent - HPV Risk Factors

Slide 40:

Lung cancer Most common cancer in the world Risk factors Prevention Lung cancer Most common cancer in the world Risk factors

Slide 44:

Stomach Cancer

Slide 46:

Breast Cancer commonest cause of death of middle aged women-developed countries (35 – 50 yrs) Risk factors Prevention Breast Cancer commonest cause of death of middle aged women-developed countries (35 – 50 yrs)

CANCER CONTROL:

CANCER CONTROL Cancer prevention is defined as active measures to decrease the incidence of cancer. The vast majority of cancer risk factors are environmental or lifestyle-related in nature, leading to the claim that cancer is a largely preventable disease By avoiding carcinogens or altering their metabolism , pursuing a lifestyle or diet that modifies cancer-causing factors and/or medical intervention ( chemoprevention , treatment of pre-malignant lesions).

CANCER CONTROL:

CANCER CONTROL The epidemiological concept of "prevention" is usually defined as either primary prevention , for people who have not been diagnosed with a particular disease. OR secondary prevention , aimed at reducing recurrence or complications of a previously diagnosed illness.

Primary prevention:

Primary prevention Lung Cancer

Primary prevention:

Primary prevention Cervical Cancer Breast cancer Stomach cancer

Primary prevention:

Primary prevention Advances in cancer research have made a vaccine designed to prevent cancer available. In 2006, the U.S. Food and Drug Administration approved a human papilloma virus vaccine, called Gardasil . The vaccine protects against four HPV types, which together cause 70% of cervical cancers and 90% of genital warts.

Primary prevention:

Primary prevention In March 2007, the US Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices (ACIP) officially recommended that females aged 11–12 receive the vaccine, and indicated that females as young as age 9 and as old as age 26 are also candidates for immunization.

Cancer Screening:

Cancer Screening Cancer screening is an attempt to detect unsuspected cancers in an asymptomatic population. Screening tests suitable for large numbers of healthy people must be relatively affordable, safe, noninvasive procedures with acceptably low rates of false positive results. If signs of cancer are detected, more definitive and invasive follow up tests are performed to confirm the diagnosis.

Cancer Screening:

Cancer Screening Methods Mass Screening by comprehensive cancer detection examination Mass Screening at single sites Selective screening - for those at special risk Pre malignant lesion can be identified Most cancers are localized in initial stages 75% occurs at accessible body sites

Screening:

Screening Screening for cancer can lead to earlier diagnosis in specific cases. Early diagnosis may lead to extended life, but may also falsely prolong the lead time to death. A number of different screening tests have been developed for different malignancies. Breast cancer screening can be done by breast self-examination .

Slide 62:

Screening of breast cancer Breast self examination(BSE) Palpation Mammography

Mammograms:

Mammograms Screening for breast cancer with mammograms has been shown to reduce the average stage of diagnosis of breast cancer in a population. Stage of diagnosis in a country has been shown to decrease within ten years of introduction of mammographic screening programs.

Screening:

Screening Colorectal cancer can be detected through fecal occult blood testing and colonoscopy , which reduces both colon cancer incidence and mortality, presumably through the detection and removal of pre-malignant polyps. Similarly, cervical cytology testing (using the Pap smear ) leads to the identification and excision of precancerous lesions. Over time, such testing has been followed by a dramatic reduction of cervical cancer incidence and mortality.

Slide 70:

Screening of cancer cervix – Pap Smear When? –start of sexual life and then every three years.

Screening:

Screening Cervical cancer screening via the Pap smear has the best cost-benefit profile of all the forms of cancer screening from a public health perspective as, being largely caused by a virus, it has clear risk factors (sexual contact), and the natural progression of cervical cancer is that it normally spreads slowly over a number of years therefore giving more time for the screening program to catch it early. Moreover, the test itself is easy to perform and relatively cheap.

Screening:

Screening Testicular self-examination is recommended for men beginning at the age of 15 years to detect testicular cancer . Prostate cancer can be screened using a digital rectal exam along with prostate specific antigen (PSA) blood testing, though some authorities (such as the US Preventive Services Task Force ) recommend against routinely screening all men.

Diagnosis:

Diagnosis Most cancers are initially recognized either because signs or symptoms appear or through screening. Neither of these lead to a definitive diagnosis, which usually requires the opinion of a pathologist , a type of physician (medical doctor) who specializes in the diagnosis of cancer and other diseases.

Investigation:

Investigation Chest x-ray showing lung cancer in the left lung. People with suspected cancer are investigated with medical tests . These commonly include blood tests , X-rays , CT scans and endoscopy .

Biopsy:

Biopsy A cancer may be suspected for a variety of reasons, but the definitive diagnosis of most malignancies must be confirmed by histological examination of the cancerous cells by a pathologist . Tissue can be obtained from a biopsy or surgery .

Treatment:

Treatment Cancer can be treated by surgery , chemotherapy , radiation therapy , immunotherapy , monoclonal antibody therapy or other methods. The choice of therapy depends upon the location and grade of the tumor and the stage of the disease, as well as the general state of the patient ( performance status ). A number of experimental cancer treatments are also under development.

CANCER CONTROL:

CANCER CONTROL Primary Prevention Secondary Prevention Control of tobacco & alcohol consumption Personal Hygiene Radiation Occupational Exposures Immunisation Foods & drugs Air pollution Treatment of precancerous lesion Legislation Cancer Education Cancer Registration Hospital based registries Population based registries Early detection of cases Treatment

Slide 84:

Thank You drmhmomin@yahoo.co.in