Explanation:
The three cancers that lead to the most deaths globally are lung (19.4%), colorectal (9%), and stomach (8.3%). The industrialized countries account for the highest rates while the lowest rates tend to be in northern Africa and southern and eastern Asia. Worldwide cancer rates are expected to increase in the near term because of aging populations and unhealthy lifestyles such as smoking and probably obesity. Tobacco use alone is responsible for 480,000 deaths per year in the U.S, according to the CDC in 2020. Although cancer rates (usually expressed as a number per 100,000 population) in the United States have declined somewhat, there has been a drastic increase in liver cancer from 2000 to 2016, according to the CDC.
Explanation:
Numerous cells undergo growth patterns that in some cases are normal responses to injury or irritation while in others they may be precursors to malignant changes.
Hyperplasia, an increase in the number of cells in a tissue, maybe a normal response in wound healing or a premalignant condition but is not a defining characteristic of cancer. Metaplasia is a potentially reversible process that involves the replacement of one type of mature cell with another not usually found it that tissue. Examples are squamous cell replacement of columnar epithelial cells in the airway of smokers or the replacement of typical cells of the distal esophagus with intestinal epithelium in the Barrett esophagus.
Dysplasia refers to a loss of uniformity of particular cells with changes of size, shape, and architecture. Malignant cell growth is usually described as anaplastic, which is marked by extreme cellular disorganization, immature forms, and prominent nuclei.
Explanation:
Overall cancer incidence has declined somewhat in men (1.5%) and has stabilized for women. Prostate cancer has declined the most in recent years; there are about 3% fewer cases per year. The incidence of liver cancer has increased the most, approximately 3.9% per year. Other cancers with reduced rates include Hodgkin lymphoma and leukemia, male lung cancer, and stomach and uterine cancers.
Melanomas, kidney, and thyroid have also shown a slightly increased incidence. Do not confuse incidence with survival rates. Cancer survival rates are usually expressed as five-year survival and include persons with disease still getting treatment and those who are alive at 5 years after diagnosis with no evidence of disease (NED). Improvements in the survival rate may reflect better treatments or perhaps earlier diagnosis.
Explanation:
The clinical description in the question is classic for lung cancer but other possible causes such as chronic obstructive lung disease, sarcoidosis, lymphoma, metastatic cancer, and tuberculosis must be ruled out. Only a biopsy can confirm a diagnosis of lung cancer. Chest X-rays may show suspicious lesions but false positives and false negatives are common and can only suggest a diagnosis. CT scans of the chest tend to show most lung cancers well and are quite helpful in localizing the lesion(s) and assisting in staging. Both bronchoscopy with brush or needle biopsy and transthoracic fine needle biopsy may provide a definite diagnosis. The latter is most useful in peripheral or diffuse lesions of the lung while the former tends to be more useful in centralized bronchogenic carcinomas. Sputum cytology may or may not be positive but usually cannot be relied upon for staging and in planning treatment.
Explanation:
Cancer of the cervix is usually squamous in nature (85% to 90%), while adenocarcinoma tends to occur in younger women and carries a worse prognosis. Lesions may be exophytic, ulcerative and necrotic, or endophytic projecting into the cervical canal. The incidence has dramatically decreased in the United States since the advent of the Pap smear in the 1940s, though worldwide it remains a significant cause of morbidity and mortality. Pap smears may report abnormal cells but the usual diagnostic methods are cone biopsy, endocervical curettage, or colposcopy-directed direct biopsy of a lesion.
Recently, DNA testing for high-risk strains of HPV, considered the cause of cervical cancer, may contribute to the diagnostic arsenal.
Explanation:
Tumor suppressor genes refer to that portion of the genetic DNA that regulates cell division. Mutation or loss of these genes may lead to enhanced cell growth and proliferation. Some of these also carry out DNA repair, so that loss will lead to unregulated cell division. The mutated gene p53 is the most common tumor suppressor gene found in human cancers, including many solid malignancies, brain tumors, and hematologic cancers. It may also interfere with apoptosis, the genetically programmed mechanism to rid the tissue of old or defective cells. In addition to p53, some other well-described tumor suppressor genes are the BRCA1 and BRCA2 genes that are associated with breast and ovarian cancer. These have a DNA repair function. Several other tumor suppressor genes act by other mechanisms.
Explanation:
According to statistics from 2013-2017, African American men had the highest cancer mortality, 227.3 per 100,000 population, while women in this group recorded 153.4.
Caucasians and then Hispanics were next most frequent, while mortality among Asian/Pacific Islanders was the lowest of the major races, 117.3 for men and 85.6 for women. The mortality rate among African American men is about 20% higher than that for Caucasians, while for women it is 12% higher in the African American community.
Interestingly, American Indians and Alaskan natives show a mortality rate lower than that of Caucasians: 173.1 versus 189.6 for men and 123.0 versus 136.4 for women.
Explanation:
In the common TNM system for assessing stage. T refers to the size or degree of invasion of the primary tumor. In gastric cancer, T1 would show invasion of the lamina propria or submucosa while T2 would show invasion of the muscularis layer. N refers to nodal involvement with NO, indicating none, and N1 and N2, indicating perigastric nodal involvement with cancer: N1 within 3 cm of the primary tumor and N2 beyond 3 cm or in distant nodes. M refers to distant metastases: MO none, M1 any metastases. Thus, answer A would be stage 1A; B stage 4 because of metastatic disease, C stage Ill, and D stage Il. Interestingly, this cancer is very common in Japan and relatively uncommon in the United States, though the incidence has been rising here recently. Dietary factors likely play a role.
Explanation:
The term for microscopic examination of the cervix is colposcopy. It is usually done after a positive Pap smear and employs a long focal length dissecting type microscope with a 10x to 16x magnification. The cervix is usually treated beforehand with a 4% acetic acid solution, which allows directed biopsy of suspicious lesions. Ovarian cancer is often suspected by pelvic examination and confirmed by laparoscopic biopsy but does not employ colposcopy. Endometrial biopsy may be useful for detecting endometrial and occasionally cervical cancer at the margin but does not involve colposcopy. Diagnosis of pancreatic cancer may be made by CT examination or laparoscopy and then needle or surgical biopsy but this also does not involve colposcopy.
Explanation:
According to the three-stage theory of carcinogenesis, the malignant transformation of normal cells involves three distinct mechanisms. An initiator substance, which may be a chemical, physical, or biological carcinogen, damages DNA that affects a genetic change.
The damaged DNA may then undergo repair and no initiation occurs. However, if the damage is permanent (mutation), it may be subject to further modification of the cell physiology by a promoter substance that can lead to alterations in the cell's proliferative capacity or inhibit apoptosis (genetically programmed cell death). Some substances such as asbestos, tobacco smoke, or alcohol have both initiator and promoter properties. It is believed there is a threshold dose for a promoter substance to alter cell physiology that in turn depends on the nature, dose, and duration of exposure.
Explanation:
Numerous factors influence the prognosis for female breast cancer, including histology and grade, tumor size, lymph node involvement, hormone-receptor status, tumor proliferative index, and several others. Lobular carcinoma is often an incidental finding that does not show up on mammography and carries an increased risk for invasive breast cancer, approximately 1% per year in either breast. Tumor size is an important marker for prognosis and tumors over 5 cm may increase the stage from II to III and worsen the prognosis. Inflammatory carcinoma of the breast often appears suddenly with skin changes but no discrete nodule and confers a poor prognosis. Tumors associated with estrogen and/or progesterone receptors tend to have a better prognosis than those that are receptor-negative.
