**Core Concept**
Hoarseness of voice, also known as dysphonia, is a symptom characterized by a change in the quality of the voice, often described as hoarse, raspy, or strained. This condition can result from various factors, including laryngeal pathology, neurological disorders, and systemic diseases.

**Why the Correct Answer is Right**
Hoarseness of voice is often an early manifestation of laryngeal cancer, particularly squamous cell carcinoma. This is due to the tumor's effect on the vocal cord's mucosa and underlying tissues, leading to changes in voice quality. The larynx's location and the vocal cords' sensitive nature make them prone to early symptoms of malignancy.

**Why Each Wrong Option is Incorrect**
**Option A:** While thyroid cancer can cause hoarseness, it is not typically associated with early symptoms in the vocal cord. Thyroid cancer may present with neck mass, voice changes, or difficulty swallowing, but these often occur later.
**Option B:** Polymyositis is a muscle disease that can cause weakness and wasting of the laryngeal muscles, leading to voice changes. However, it is not a primary cause of hoarseness in the early stages of the disease.
**Option C:** Laryngitis, an inflammation of the larynx, can cause hoarseness, but it is usually a self-limiting condition that resolves with treatment. Laryngitis is not typically associated with early cancer symptoms.

**Clinical Pearl / High-Yield Fact**
When evaluating a patient with hoarseness, it is essential to perform a thorough head and neck examination, including inspection of the larynx, to identify potential laryngeal pathology.

**Correct Answer: D. Laryngeal cancer. Laryngeal cancer.**