Principles of Cancer Therapy — MCQs

10 questions

Which of the following stages of Breast Cancer corresponds to the following features: a breast mass of 6 x 3 cm, ipsilateral supraclavicular lymph node involvement, and distant metastasis that cannot be assessed?

A 70 year old male complaining of per rectal bleeding was diagnosed with rectal/anorectal cancer. The distal margin of the tumor was 5 cm from the anal verge. The treatment of choice would be -

Which compound is not considered as a radiosensitizer?

Point A and point B Manchester locations are important for treatment of which cancer –

Primary treatment for localized malignant melanoma is

Radiosensitizers are all Except

Intraoperative radiation therapy (IORT) is most commonly used in which of the following cancers?

Continuous GnRH therapy is used in All EXCEPT.

Gynecomastia is seen in all except;

Q10

Which is the most reliable diagnostic method for staging esophageal cancer?

Principles of Cancer Therapy Indian Medical PG Practice Questions and MCQs

Question 1: Which of the following stages of Breast Cancer corresponds to the following features: a breast mass of 6 x 3 cm, ipsilateral supraclavicular lymph node involvement, and distant metastasis that cannot be assessed?

A. T4 N3 MX
B. T4 N1 M1
C. T4 N0 M0
D. T3 N3c MX (Correct Answer)

Explanation: ***T3 N3c MX*** - A **breast mass of 6 x 3 cm** indicates a T3 tumor (tumor size > 5 cm). - **Ipsilateral supraclavicular lymph node involvement** is classified as N3c disease. **Distant metastasis that cannot be assessed** is denoted by MX. *T4 N3 MX* - A **T4 classification** is reserved for tumors with direct extension to the chest wall or skin, or inflammatory breast cancer, which is not mentioned here. - While N3c and MX are correct for the nodal and metastatic status, the T stage is inaccurate based on the provided tumor size. *T4 N1 M1* - A **T4 classification** is incorrect as the mass size alone (6 x 3 cm) does not meet T4 criteria. - **N1** denotes involvement of 1-3 axillary lymph nodes, which is less extensive than supraclavicular involvement (N3c). **M1** indicates confirmed distant metastasis, but the question states it "cannot be assessed" (MX). *T4 N0 M0* - **T4** is incorrect, as this stage is for direct chest wall/skin involvement or inflammatory breast cancer. - **N0** signifies no regional lymph node metastasis, contradicting the presence of supraclavicular lymph node involvement. **M0** indicates no distant metastasis, whereas the question specifies it cannot be assessed (MX).

Question 2: A 70 year old male complaining of per rectal bleeding was diagnosed with rectal/anorectal cancer. The distal margin of the tumor was 5 cm from the anal verge. The treatment of choice would be -

A. Palliative Radiotherapy
B. Low anterior resection (Correct Answer)
C. Local Excision
D. Abdominoperineal resection

Explanation: ***Low anterior resection*** - A tumor located 5 cm from the anal verge is considered a **low rectal tumor**, which is typically amenable to a **low anterior resection** with sphincter preservation. - This procedure aims for complete tumor removal while preserving anal function, which is often achievable when the distal margin allows for a safe distal resection margin (usually 1-2 cm). *Palliative Radiotherapy* - This is typically reserved for patients with advanced, **unresectable disease** or those who are not candidates for surgery due to comorbidities, aiming to alleviate symptoms rather than cure. - The scenario describes a potentially resectable tumor, making curative surgery the preferred initial approach. *Abdominoperineal resection* - This procedure involves the removal of the rectum, anus, and creation of a permanent colostomy, typically reserved for very **low rectal tumors** that are extremely close to or involve the anal sphincter, and cannot safely achieve a negative distal margin with sphincter preservation. - A tumor 5 cm from the anal verge usually allows for a sphincter-sparing procedure like low anterior resection. *Local Excision* - **Local excision (transanal excision)** is suitable for very superficial, small, well-differentiated tumors without lymph node involvement, typically T1N0M0 tumors. - The question does not provide details on tumor depth or nodal status, but a 5 cm tumor usually indicates a need for a more comprehensive resection to ensure oncological clearance.

Question 3: Which compound is not considered as a radiosensitizer?

A. Hyperbaric oxygen
B. Misonidazole
C. Amifostine (Correct Answer)
D. Idoxuridine

Explanation: ***Amifostine*** - **Amifostine** is a **radioprotector**, meaning it selectively protects healthy cells from the damaging effects of radiation, rather than enhancing radiation's effect on tumor cells. - It works by being dephosphorylated by alkaline phosphatase in normal tissues to an active thiol metabolite that scavenges **free radicals** generated by radiation. *Hyperbaric oxygen* - **Hyperbaric oxygen** increases the amount of dissolved oxygen in tissues, which is a potent **radiosensitizer**. - **Oxygen** enhances the formation of **free radicals** and fixes radiation-induced DNA damage, making tumor cells more susceptible to radiation. *Misonidazole* - **Misonidazole** is a **hypoxic radiosensitizer** that mimics oxygen, becoming relatively toxic under hypoxic conditions (common in tumors). - It forms **free radicals** and binds to cellular macromolecules when reduced by nitroreductases in hypoxic cells, thereby enhancing the effects of radiation. *Idoxuridine* - **Idoxuridine** is a **halogenated pyrimidine** that acts as a radiosensitizer by being incorporated into DNA in place of thymidine. - This incorporation sensitizes the DNA to radiation by making it more susceptible to **strand breaks** and other damage.

Question 4: Point A and point B Manchester locations are important for treatment of which cancer –

A. Vagina
B. Cervix (Correct Answer)
C. Ovary
D. Uterus

Explanation: ***Cervix*** - **Point A** and **Point B Manchester** locations are historical references used in **brachytherapy** for **cervical cancer**, defining critical dose points within the pelvis. - These points help guide the placement of radiation sources to ensure adequate tumor coverage while sparing surrounding healthy tissues. *Vagina* - While radiation therapy is used for vaginal cancer, the **Manchester system's Point A and B** are specifically defined for cervical anatomy, not primarily for vaginal tumors. - Different dosimetry systems or specific vaginal applicators are often used for vaginal brachytherapy. *Ovary* - Ovarian cancer is primarily treated with **surgery and chemotherapy**; external beam radiation is sometimes used, but brachytherapy with **Point A and B** is not a standard approach. - The anatomical location of the ovaries makes brachytherapy less suitable for delivering targeted, high-dose radiation compared to cervical cancer. *Uterus* - Endometrial (uterine) cancer treatment may involve brachytherapy, but it typically uses different applicators (e.g., **tandem and ovoids** or cylinders) and dose specifications that are distinct from the Manchester system's **Point A and B** for the cervix. - The geometry and treatment volumes for uterine brachytherapy are different due to the distinct anatomy and tumor spread patterns.

Question 5: Primary treatment for localized malignant melanoma is

A. Wide excision (Correct Answer)
B. Radiotherapy
C. Excision
D. Chemotherapy

Explanation: ***Wide excision*** - This is the **primary treatment** for localized malignant melanoma, aiming to completely remove the tumor along with a surrounding margin of healthy tissue to reduce recurrence risk. - The excisional margin width depends on the **Breslow depth** (tumor thickness). *Radiotherapy* - Not the primary treatment for localized melanoma, as melanoma cells are often **radioresistant**. - It may be used as **adjuvant therapy** for local control in cases of positive margins or nodal involvement, or for palliative care in metastatic disease. *Excision* - While excision is part of the treatment, the term **"wide excision"** specifically implies removing a sufficient margin of healthy tissue around the tumor. - Simple excision without appropriate margins is generally inadequate for malignant melanoma and carries a **high risk of local recurrence**. *Chemotherapy* - It is generally **not the first-line treatment** for localized melanoma due to limited efficacy and significant side effects. - Chemotherapy agents are typically reserved for **advanced or metastatic melanoma** and are often replaced by targeted therapies or immunotherapy in modern practice.

Question 6: Radiosensitizers are all Except

A. Metronidazole
B. Nimorazole
C. Cisplatin
D. Amifostine (Correct Answer)

Explanation: ***Amifostine*** - Amifostine is a **radioprotector**, meaning it helps protect healthy tissues from the damaging effects of radiation. - It does this by selectively scavenging **free radicals** in normal cells, reducing radiation-induced toxicity. *Metronidazole* - **Metronidazole** is a well-known **radiosensitizer**, particularly effective in hypoxic (low-oxygen) tumor environments. - It enhances the effectiveness of radiation therapy by forming **toxic free radicals** when metabolized in hypoxic cells, thereby increasing DNA damage. *Nimorazole* - **Nimorazole** is another **nitroimidazole radiosensitizer**, similar in action to metronidazole. - It is used to improve the outcome of radiation therapy in certain cancers, especially in **hypoxic tumors**, by increasing their sensitivity to radiation. *Cisplatin* - **Cisplatin** is a platinum-based **chemotherapeutic agent** that also acts as a potent **radiosensitizer**. - It enhances the cytotoxic effects of radiation by interfering with **DNA repair mechanisms** and inducing DNA damage more effectively when combined with radiation.

Question 7: Intraoperative radiation therapy (IORT) is most commonly used in which of the following cancers?

A. Ca Thyroid
B. Ca Pancreas (Correct Answer)
C. Ca Cervix
D. Ca Breast

Explanation: ***Ca Pancreas*** - **Intraoperative radiation therapy (IORT)** is frequently employed for **pancreatic cancer** due to its deep-seated location and locally advanced nature at presentation. - IORT allows for a **high dose of radiation** (10-20 Gy) to be delivered directly to the tumor bed and involved lymph nodes at the time of surgery, while critical structures like the stomach, duodenum, and kidneys can be retracted or shielded. - Particularly useful in **borderline resectable or locally advanced cases** where complete resection margins are difficult to achieve. - Used in specialized centers as part of multimodal therapy to improve local control. *Ca Thyroid* - **Thyroid cancer** is generally treated with surgery (thyroidectomy) followed by **radioactive iodine (RAI) therapy** for papillary and follicular types, not typically IORT. - The thyroid gland's superficial location and high avidity for iodine make RAI an effective targeted therapy. - IORT has no established role in standard thyroid cancer management. *Ca Cervix* - **Cervical cancer** treatment involves surgery, **external beam radiation therapy (EBRT)**, and **brachytherapy**, which places radioactive sources directly into or near the tumor. - Brachytherapy is superior for cervical cancer due to excellent dose distribution to the cervix and parametrium. - IORT is not a standard approach for primary cervical cancer, though it might be considered in select recurrent cases. *Ca Breast* - For **breast cancer**, IORT has gained significant traction, particularly for **early-stage disease** (T1-T2, node-negative) as an alternative to 5-6 weeks of external beam radiation. - **TARGIT-A and ELIOT trials** have established IORT as a viable option for partial breast irradiation during breast-conserving surgery. - While increasingly used globally with dedicated devices (INTRABEAM, ELIOT), it remains a **selective option** rather than universally applied. - The indication is more specific (favorable early-stage tumors) compared to the broader applications in pancreatic cancer where dose escalation and organ sparing are critical challenges.

Question 8: Continuous GnRH therapy is used in All EXCEPT.

A. Precocious puberty
B. Prostate cancer
C. Endometriosis
D. Male infertility (Correct Answer)

Explanation: ***Male infertility*** - Continuous **GnRH therapy downregulates** the pituitary leading to reduced LH and FSH secretion, which would **impair spermatogenesis** and thus worsen male infertility, not treat it. - While GnRH agonists can be used to suppress male fertility for **contraceptive purposes**, they are not used to treat male infertility, which often requires stimulation of gonadotropins. *Precocious puberty* - Continuous GnRH therapy (agonists) is used to **suppress premature puberty** by desensitizing the GnRH receptors in the pituitary. - This effectively **reduces gonadotropin release** and subsequent sex hormone production, halting the progression of puberty. *Prostate cancer* - Continuous GnRH agonists are a cornerstone of treatment for **hormone-sensitive prostate cancer**, as they create a state of chemical castration. - By **downregulating LH production**, they reduce testosterone synthesis from the testes, starving the cancer of growth-promoting hormones. *Endometriosis* - Continuous GnRH agonists are used to induce a **hypoestrogenic state**, which is crucial in managing endometriosis. - By **suppressing ovarian estrogen production**, they lead to atrophy of endometrial implants and relieve pain symptoms.

Question 9: Gynecomastia is seen in all except;

A. Kidney failure
B. Liver failure
C. Stilbestrol therapy for prostate cancer
D. Teratoma of the testis
E. Hormonal
F. Leprosy (Correct Answer)
. Idiopathic
. Anorchism and After castration
. Klinefelter's syndrome

Explanation: Leprosy - While leprosy can affect various endocrine glands, **gynecomastia is not a typical or direct manifestation** of the disease. - Its primary impact is on the peripheral nerves, skin, and upper respiratory tract, not directly on estrogen-androgen balance. *Kidney failure* - **Chronic kidney disease** often leads to **hormonal imbalances**, including increased prolactin and decreased testosterone, which can cause gynecomastia. - The altered metabolism and excretion of hormones contribute to this endocrine dysfunction. *Liver failure* - The liver is crucial for metabolizing **estrogens** and other hormones; **liver failure** leads to reduced estrogen breakdown and elevated circulating levels. - This **increased estrogen-to-androgen ratio** promotes breast tissue development in males. *Stilbestrol therapy for prostate cancer* - **Stilbestrol is a synthetic estrogen** often used as part of androgen deprivation therapy for prostate cancer. - Administering exogenous estrogen directly **stimulates breast tissue growth**, causing gynecomastia. *Teratoma of the testis* - Certain **testicular tumors**, including some teratomas, can produce **human chorionic gonadotropin (hCG)** [1]. - Elevated hCG can **stimulate Leydig cells to produce estrogen** and can also directly stimulate aromatase activity, leading to gynecomastia. *Hormonal* - This category generally refers to conditions where there is an **imbalance between estrogen and androgen levels**, favoring estrogenic effects. - **Any condition that increases estrogen or decreases testosterone** can lead to gynecomastia. *Idiopathic* - **Idiopathic gynecomastia** refers to cases where no identifiable underlying cause can be found despite thorough investigation. - It's a diagnosis of exclusion, signifying that the exact hormonal imbalance or mechanism remains unknown. *Anorchism and After castration* - Both anorchism (absence of testes) and castration (surgical removal of testes) result in a **severe deficiency of testosterone**. - Without sufficient androgen production, the **relative effect of even normal estrogen levels becomes dominant**, leading to gynecomastia. *Klinefelter's syndrome* - **Klinefelter's syndrome (47, XXY)** is a chromosomal disorder characterized by **testicular dysfunction**, leading to primary hypogonadism [2]. - This results in **low testosterone and relatively high estrogen levels** [3], a classic hormonal imbalance that causes gynecomastia.

Question 10: Which is the most reliable diagnostic method for staging esophageal cancer?

A. MRI
B. Endoscopic ultrasound (Correct Answer)
C. CT scan
D. Thoracoscopy

Explanation: ***Endoscopic ultrasound*** - **Endoscopic ultrasound (EUS)** provides the most accurate and reliable local staging of esophageal cancer by visualizing the depth of tumor invasion into the esophageal wall and assessing regional lymph node involvement. - Its high-frequency ultrasound transducer allows for detailed imaging of the esophageal wall layers and surrounding structures, crucial for determining T and N stages. *MRI* - While MRI can be useful for assessing **distant metastases** and involvement of adjacent organs, it is generally less effective than EUS for determining the precise depth of local esophageal wall invasion. - Its role is more prominent in later stages or when assessing response to neoadjuvant therapy rather than primary local staging. *CT scan* - A **CT scan** is excellent for detecting **distant metastases** and assessing the general extent of the disease, including involvement of surrounding structures and distant lymph nodes. - However, its resolution is insufficient to accurately determine the exact depth of tumor invasion within the esophageal wall, making it less reliable for precise T staging than EUS. *Thoracoscopy* - **Thoracoscopy** is an invasive surgical procedure primarily used for direct visualization and biopsy of suspicious lesions in the chest cavity, or for mediastinal lymph node staging, particularly when other methods are inconclusive. - It is not considered a primary diagnostic method for initial staging of esophageal cancer due to its invasiveness and inability to assess all aspects of local and regional spread as comprehensively as EUS.

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