A patient with occupational exposure to benzene presents with repeated infections, easy fatigability, weight loss, and evening rise to temperature. This occupational exposure will predispose him to which of the following cancers?

Correct Answer: B. Leukemia

Benzene is a well-established occupational carcinogen with a Class 1 carcinogenic potential (IARC Group 1). The clinical presentation—repeated infections (immunosuppression), easy fatigability, weight loss, and evening fever—is pathognomonic for benzene-induced aplastic anemia progressing to acute myeloid leukemia (AML). Benzene's metabolite, hydroquinone, directly damages hematopoietic stem cells in the bone marrow, causing dose-dependent myelotoxicity. This leads to initial pancytopenia (explaining infections and fatigue), followed by clonal expansion of abnormal myeloid precursors. The evening fever reflects leukemic burden and cytokine release. Benzene exposure is the leading occupational cause of leukemia globally and in India (particularly in workers in petroleum refineries, printing industries, and shoe manufacturing). The latency period is typically 5–15 years post-exposure. Unlike other occupational carcinogens, benzene has a specific tropism for hematopoietic tissue, not epithelial surfaces. This is why skin, lung, and bladder cancers are not the primary risk—they require direct epithelial contact or systemic absorption patterns different from benzene's bone marrow targeting.

Why the other options are wrong

A. Skin cancer — Benzene does not cause skin cancer. While benzene can cause dermatitis with chronic exposure, it does not undergo the metabolic activation required for epithelial carcinogenesis. Skin cancers are typically associated with UV exposure or polycyclic aromatic hydrocarbons (PAHs) in tar/pitch, not benzene. This is an NBE distractor using the 'occupational exposure' stem to mislead students into thinking any occupational carcinogen causes skin cancer. C. Lung cancer — Lung cancer is not the primary malignancy from benzene exposure. While inhalation is the main route of benzene absorption, the metabolite hydroquinone preferentially targets bone marrow stem cells, not lung epithelium. Lung cancer from occupational exposure is classically linked to asbestos, silica, or radon—not benzene. This option exploits the fact that benzene is inhaled, but ignores its organ-specific carcinogenic mechanism. D. Bladder cancer — Bladder cancer is not associated with benzene exposure. Bladder cancer is the hallmark malignancy of aniline dye and aromatic amine exposure (e.g., 2-naphthylamine, benzidine), not benzene itself. This is a classic NBE trap: both are aromatic compounds, but their carcinogenic targets differ fundamentally. Benzene → leukemia; aromatic amines → bladder cancer.

High-Yield Facts

Mnemonics

BENZENE = BONE MARROW Benzene's metabolite (hydroquinone) selectively damages bone marrow hematopoietic cells → leukemia. Not skin, lung, or bladder. Remember: benzene is hematotoxic, not epitheliotoxic. AROMATIC CARCINOGENS: SITE-SPECIFIC Benzene → Leukemia (bone marrow). Aniline/Benzidine → Bladder cancer. Asbestos → Lung/mesothelioma. Silica → Lung. Each aromatic/occupational agent has a specific target organ.

NBE Trap

NBE pairs benzene with "occupational exposure" to lure students into choosing skin or lung cancer (the most common occupational malignancies). The trap is forgetting that benzene's metabolite hydroquinone has bone marrow tropism, not epithelial tropism. Additionally, the aromatic amine–bladder cancer association is confused with benzene by students who don't distinguish between different aromatic compounds.

Clinical Pearl

In Indian occupational health clinics, benzene-exposed workers (especially in unregulated small-scale printing and shoe industries) often present with fatigue and recurrent infections before leukemia is diagnosed. The evening fever + pancytopenia triad should immediately raise suspicion for benzene-induced hematologic malignancy, prompting urgent bone marrow examination and occupational history review.

_Reference: Robbins Ch. 7 (Environmental and Nutritional Pathology); KD Tripathi Ch. 57 (Toxicology); Harrison Ch. 87 (Acute Myeloid Leukemia)_