Cancer Epidemiology and Prevention — MCQs
Which of the following is not directly implicated as a cause of squamous cell carcinoma of the head and neck?
A new drug has been introduced into the market which was found to decrease mortality but it does not cure the disease. Which of the following is a true statement regarding prevalence and incidence?
The term 'Primary Prevention' includes all of the following except
The lung carcinoma most common in non-smokers is?
Which of the following is the MOST significant risk factor for carcinoma of the cervix?
The carcinogenic chemical that has a very long latent period is –
Screening for oral cancer comes under which level of prevention?
Which of the following is not considered an occupational cancer?
What is the prevalence in a given population of 1000, where there are 50 new cases of lung cancer and 100 old cases of lung cancer in the same population?
The image below shows the life cycle of a virus. Which of the proteins of the virus act as oncogenes?
Cancer Epidemiology and Prevention Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following is not directly implicated as a cause of squamous cell carcinoma of the head and neck?
- A. EBV
- B. HPV
- C. Betel Nut
- D. Vitamin A deficiency (Correct Answer)
Explanation: ***Vitamin A*** - Vitamin A deficiency is associated with increased risk of squamous metaplasia but not a direct cause of squamous cell carcinoma in the head and neck. - Adequate levels of Vitamin A are actually protective against various epithelial cancers. *EBV* - Epstein-Barr Virus (EBV) is linked to certain types of cancers, including nasopharyngeal carcinoma, but is not a major causative factor for squamous cell carcinoma [1]. - It can contribute to **lymphoproliferative disorders** but not primarily to squamous cell carcinoma of the head and neck [1]. *HPV* - Human Papillomavirus (HPV), particularly types 16 and 18, are recognized as significant contributors to oropharyngeal squamous cell carcinoma [1]. - HPV infection can lead to **malignant transformation** of epithelial cells [1]. *Betel Nut* - Betel nut chewing is a well-established risk factor for oral squamous cell carcinoma, associated with its carcinogenic properties [2]. - It can cause **oral lesions** and dysplasia, contributing significantly to the etiology of head and neck cancers [2].
Question 2: A new drug has been introduced into the market which was found to decrease mortality but it does not cure the disease. Which of the following is a true statement regarding prevalence and incidence?
- A. Increase in prevalence (Correct Answer)
- B. Decrease in incidence
- C. Decrease in prevalence
- D. Increase in incidence
Explanation: ***Increase in prevalence*** - A drug that decreases mortality without curing the disease means people **live longer with the condition**, thus increasing the duration of disease - **Prevalence = Incidence × Duration**: Since duration increases while incidence remains constant, prevalence increases - More existing cases accumulate over time as fewer patients die from the disease *Decrease in incidence* - **Incidence** refers to the rate at which **new cases** develop in a population - This drug affects survival of existing cases, not the development of new cases - Since the drug neither prevents nor promotes new cases, **incidence remains unchanged** (not decreased) *Decrease in prevalence* - Prevalence would decrease if the drug **cured the disease** (removing people from the diseased pool) or if **mortality increased** - The scenario describes the opposite: decreased mortality without cure, which **increases** prevalence *Increase in incidence* - This would mean more new cases are developing over time - The drug affects **survival** of existing cases, not the **rate of new diagnoses** - Incidence remains unchanged, not increased
Question 3: The term 'Primary Prevention' includes all of the following except
- A. Health education about balanced diet
- B. Early detection and treatment of hypertension (Correct Answer)
- C. Immunization against measles
- D. Provision of safe drinking water
Explanation: ***Early detection and treatment of hypertension*** - This describes **secondary prevention**, which focuses on **early diagnosis and prompt treatment** of disease to prevent progression and complications. - Screening programs for hypertension and initiating treatment after detection aim to **interrupt the disease process** rather than prevent its initial occurrence. - Secondary prevention reduces the severity and complications of an existing condition. *Immunization against measles* - This is a classic example of **primary prevention** that prevents the initial occurrence of disease by building immunity before exposure. - Vaccination programs are the cornerstone of primary prevention in public health, protecting individuals before they contract the infection. *Health education about balanced diet* - Dietary counseling and nutrition education are **primary prevention** strategies that promote healthy behaviors and prevent the onset of nutrition-related disorders. - This includes preventing obesity, diabetes, cardiovascular diseases, and micronutrient deficiencies through appropriate dietary practices. *Provision of safe drinking water* - Ensuring access to safe water is a fundamental **primary prevention** measure that prevents waterborne diseases like cholera, typhoid, hepatitis A, and diarrheal diseases. - Environmental modifications to eliminate disease risk factors are key components of primary prevention in community medicine.
Question 4: The lung carcinoma most common in non-smokers is?
- A. Large cell
- B. Adenocarcinoma (Correct Answer)
- C. Small cell carcinoma
- D. Squamous cell carcinoma
Explanation: ***Adenocarcinoma*** - **Adenocarcinoma** is the most common lung cancer histology type found in non-smokers, often associated with **female gender** and **younger age** demographics. - Frequently linked to **environmental factors** like exposure to radon and air pollution, rather than smoking. *Large cell* - This type is generally associated with **poor differentiation** and higher rates of metastasis, but not specifically prevalent in non-smokers. - Often arises in **smokers**, reflecting a different epidemiological profile compared to adenocarcinoma. *Squamous cell carcinoma* - Strongly correlated with **cigarette smoking** [1] and typically originates from the **central airways**. - Commonly associated with **keratinization**, making it less frequent in the non-smoking population. *Small cell carcinoma* - Most commonly seen in **heavy smokers**, characterized by **rapid growth** and **early metastasis**. - It does not represent the predominant type in non-smokers, further supporting adenocarcinoma as the most common in that group. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 336-337.
Question 5: Which of the following is the MOST significant risk factor for carcinoma of the cervix?
- A. Multiparity
- B. HIV infection
- C. None of the options (Correct Answer)
- D. Smoking
Explanation: ***None of the options*** - The **MOST significant risk factor** for cervical carcinoma is **persistent infection with high-risk HPV types** (especially HPV 16 and 18), which is found in >99% of cervical cancers and is considered the **necessary cause**. - Since **HPV infection** is not listed among the options, none of the given choices represents the most significant risk factor. - While HIV, smoking, and multiparity are all associated with increased cervical cancer risk, they are **secondary factors** that work primarily by affecting HPV persistence or acting as co-factors. *HIV infection* - **HIV infection** is an important risk factor as it compromises immune surveillance and reduces the ability to clear **HPV infections**, leading to persistent high-risk HPV and progression to CIN and invasive cancer. - However, HIV increases risk **through its effect on HPV persistence**, not as an independent primary cause. - Without HPV, HIV alone does not cause cervical cancer. *Smoking* - **Smoking** is an independent co-factor that increases cervical cancer risk, with tobacco carcinogens found in cervical mucus acting synergistically with **HPV**. - It is a secondary risk factor, not the primary cause. *Multiparity* - **Multiparity** shows a weak association with cervical cancer risk, possibly related to hormonal changes or increased HPV exposure. - It is the least significant among the listed factors and is not a primary driver of cervical carcinogenesis.
Question 6: The carcinogenic chemical that has a very long latent period is –
- A. Benzopyrene
- B. Asbestos (Correct Answer)
- C. Vinyl chloride
- D. Estrogens
Explanation: ***Asbestos*** - Asbestos exposure is famously associated with a **very long latent period** (often 20-50 years) before the development of cancers like **mesothelioma** and lung cancer. - This characteristic makes it challenging to link past exposure directly to current disease, leading to significant public health and legal implications. *Benzopyrene* - Benzopyrene (a polycyclic aromatic hydrocarbon found in cigarette smoke and industrial emissions) is a potent carcinogen, but its latency period, while significant, is generally shorter than that of asbestos. - It is primarily associated with **lung cancer** and other cancers related to direct exposure. *Vinyl chloride* - Vinyl chloride is a well-known carcinogen, primarily implicated in **hepatic angiosarcoma**; however, its latent period is typically shorter than that observed with asbestos exposure. - Exposure is usually occupational, and the associated cancers often manifest within 10-20 years. *Estrogens* - Estrogens, particularly prolonged or unopposed exposure (e.g., in some hormone replacement therapies or conditions like obesity), are linked to an increased risk of **endometrial** and **breast cancers**. - While these cancers have latent periods, they are generally not as exceptionally long as those associated with asbestos.
Question 7: Screening for oral cancer comes under which level of prevention?
- A. Tertiary level
- B. Primary level
- C. Secondary level (Correct Answer)
- D. None of the options
Explanation: ***Secondary level*** - **Screening** aims for **early detection and prompt treatment** of a disease, which is the definition of secondary prevention. - In the context of oral cancer, screening involves examinations to identify **precancerous lesions** or early-stage cancer to improve prognosis. *Tertiary level* - **Tertiary prevention** focuses on **reducing the impact** of an established disease and **preventing recurrence or complications**. - Examples include rehabilitation for cancer patients or preventing metastasis after initial treatment. *Primary level* - **Primary prevention** is about **preventing the onset** of a disease altogether. - Examples for oral cancer include **smoking cessation campaigns** or **HPV vaccination** to prevent infection linked to oral cancers. *None of the options* - This option is incorrect because oral cancer screening clearly falls under one of the established levels of prevention. - The framework of primary, secondary, and tertiary prevention is comprehensive for public health interventions.
Question 8: Which of the following is not considered an occupational cancer?
- A. Lung
- B. Breast (Correct Answer)
- C. Liver
- D. Bladder
Explanation: ***Breast*** - Breast cancer has a **limited association** with occupational exposure compared to other cancers [1], mainly influenced by genetic and hormonal factors. - While some studies suggest minor correlations, the **impact of environment** and occupation is considerably less significant for breast cancer. *Bladder* - Strongly linked to **aromatic amines** from dyes and rubber manufacturing [2], as well as exposures to **chemical irritants**. - The **occupational risk** is well-documented, particularly among workers in the chemical industry [1]. *Liver* - Associated with **chemical exposures** such as aflatoxins and certain industrial solvents, particularly in the manufacturing and agriculture sectors. - Significant occupational hazards, like **vinyl chloride**, have demonstrated a clear link to liver cancer [2]. *Lung* - Closely tied to **asbestos** [1][3], **smoke**, and other pollutants, highlighting the role of industrial environments in increasing risk. - **Occupational exposure** remains a major contributor to lung cancer rates, particularly in mining and construction [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, p. 286. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 217-218. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 221-222.
Question 9: What is the prevalence in a given population of 1000, where there are 50 new cases of lung cancer and 100 old cases of lung cancer in the same population?
- A. 1.50%
- B. 15% (Correct Answer)
- C. 150
- D. 13%
Explanation: ***Correct: 15%*** - **Prevalence** is the proportion of a population living with a disease at a specific time point. It includes both new and existing (old) cases. - **Calculation:** Total cases = 50 (new cases) + 100 (old cases) = 150 cases - **Prevalence rate** = (150 / 1000) × 100% = **15%** - Prevalence answers the question: "What proportion of the population has the disease right now?" *Incorrect: 1.50%* - This value represents a calculation error, likely from dividing 150 by 10,000 instead of 1,000 - It underestimates the actual prevalence by a factor of 10 - Would only be correct if there were 15 total cases, not 150 *Incorrect: 150* - This is the **absolute count** of individuals with lung cancer (both new and old cases) - Prevalence must be expressed as a **proportion or percentage**, not a raw count - Raw counts cannot be compared across populations of different sizes *Incorrect: 13%* - This would only be correct if there were 130 total cases, not 150 - This miscalculation fails to properly sum the new cases (50) and old cases (100) - The arithmetic is incorrect: 50 + 100 ≠ 130
Question 10: The image below shows the life cycle of a virus. Which of the proteins of the virus act as oncogenes?
- A. L1, L2
- B. E1, E2, E5
- C. E1, E2
- D. E6, E7 (Correct Answer)
Explanation: ***E6, E7*** - The **E6** and **E7** proteins of high-risk human papillomaviruses (HPVs) are considered **oncogenes** because they interfere with critical tumor suppressor pathways [1][2]. - **E6** promotes the degradation of **p53**, a tumor suppressor protein, while **E7** inactivates **retinoblastoma protein (pRb)**, leading to uncontrolled cell proliferation and increased risk of malignant transformation [2]. *L1, L2* - **L1** and **L2** are **late proteins** (structural proteins) that form the **viral capsid** (outer shell) of the HPV virion. - They are essential for assembling new viral particles but do not directly contribute to the oncogenic process by disrupting host cell cycle regulation. *E1, E2, E5* - **E1** is involved in **viral DNA replication**, acting as a helicase and ATPase. - **E2** regulates **viral gene expression** and DNA replication, while **E5** is a small transmembrane protein that can contribute to cell growth but is generally considered less potent in oncogenesis than E6 and E7, and its exact role varies by HPV type. *E1, E2* - **E1** is critical for **viral DNA replication**, and **E2** regulates viral gene transcription and DNA replication. - While important for the viral life cycle, neither E1 nor E2 are the primary drivers of oncogenesis in the way E6 and E7 are, as they do not directly target key tumor suppressor proteins like p53 and pRb. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Female Genital Tract, pp. 1007-1008. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Neoplasia, pp. 334-335.
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