Losing one’s voice, medically termed dysphonia or, in its complete absence, aphonia, is a frequent and often distressing symptom for individuals with cancer. This change can manifest as hoarseness, a breathy quality, or a significant reduction in vocal power and pitch. When the function or structure of the vocal cords within the larynx (voice box) is compromised, the resulting vocal change indicates that underlying physiological processes have been disrupted. Understanding these mechanisms is a significant step toward managing and mitigating this side effect.
How Tumors Directly Affect the Voice
The physical presence of a tumor can directly interfere with the neurological and mechanical systems required for normal voice production. Voice loss occurs when a malignant mass compresses or invades the recurrent laryngeal nerve (RLN), the primary nerve controlling nearly all laryngeal muscles. Because the RLN branches from the vagus nerve and travels down into the chest before looping back up, it is vulnerable to tumors in the neck, chest, and mediastinum.
Tumors in the lung, particularly Pancoast tumors, frequently cause vocal cord paralysis because the left RLN has a longer path, looping under the aortic arch. Compression of the nerve anywhere along its route blocks the signal to the vocal cord muscle, leading to paralysis on that side. This paralysis prevents the vocal cord from closing fully, causing a weak, breathy voice and sometimes an ineffective cough. Tumors originating in the larynx itself or nearby structures like the thyroid can also directly obstruct airflow or inhibit cord movement, causing immediate hoarseness.
Vocal Cord Damage from Cancer Treatments
Therapeutic interventions, while targeting cancer, can cause damage to the vocal apparatus, leading to voice changes.
Surgery
Surgery performed in areas like the neck, chest, or thyroid carries a risk of trauma to the recurrent laryngeal nerve (RLN). The nerve can be stretched, bruised, or partially severed, resulting in temporary or permanent vocal cord paresis or paralysis. The extent of the nerve injury dictates the level of vocal cord immobility.
Radiation Therapy
Radiation therapy directed at tumors in the head and neck region is a frequent cause of both acute and long-term dysphonia. During treatment, the ionizing radiation causes inflammation of the laryngeal tissues, a condition known as radiation laryngitis, which leads to hoarseness. Over time, the irradiated tissue can undergo fibrosis, a process where normal, elastic tissue is replaced by stiff, inelastic scar tissue. This fibrosis reduces the vocal cords’ flexibility, altering their vibratory capacity. This results in a permanently rough or strained voice quality.
Chemotherapy and Targeted Agents
Chemotherapy and targeted agents can contribute to laryngeal dysfunction through neurological or inflammatory pathways. Certain chemotherapy drugs, such as platinum compounds or taxanes, are known to cause peripheral neuropathy, which affects the small nerves supplying the voice box. Specific targeted therapies may also cause inflammation or tissue changes that impair vocal cord function. These systemic drug toxicities lead to generalized voice changes that often resolve once the causative agent is discontinued.
Systemic Causes of Voice Changes
Voice changes can also arise from body-wide effects of the cancer or its treatment. Cancer-related fatigue, a persistent exhaustion not relieved by rest, can lead to a weaker voice because the patient lacks the muscular energy to project sound effectively. The voice may sound soft, strained, or run out of air quickly during conversation. This generalized weakness directly impacts the respiratory and laryngeal muscles required for phonation.
Dehydration is another common systemic factor that severely compromises vocal quality. Many cancer treatments and the disease itself can lead to a dry mouth (xerostomia) and overall reduced body hydration. The vocal cords rely on a thin layer of mucosal lubrication for optimal, effortless vibration. When this layer dries out, the cords rub together more forcefully, leading to vocal strain and a rough, raspy sound.
A weakened immune system, often due to chemotherapy, increases the risk of opportunistic infections like oral candidiasis (thrush), which can spread to the throat and larynx. Inflammation of the mouth and throat lining, or mucositis, is also a painful side effect of radiation and chemotherapy. This inflammation can extend to the laryngeal area, making vocal cord movement physically painful, leading patients to speak with a forced whisper or avoid speaking altogether.
When to Consult a Doctor About Voice Loss
Any new or worsening change in voice warrants medical attention, especially for cancer patients. Patients should consult their care team if hoarseness lasts for more than two to three weeks, suggesting a persistent underlying issue. Immediate evaluation is necessary if voice changes are accompanied by difficulty breathing, pain when swallowing or speaking, or a newly discovered lump in the neck.
The medical team, often including a speech-language pathologist (SLP), performs a detailed vocal assessment. Management is multifaceted, beginning with increased hydration to maintain mucosal lubrication and voice rest to reduce strain. An SLP provides voice therapy, offering exercises to strengthen and coordinate the remaining vocal muscles, improving voice quality and projection. Addressing the root cause, such as managing infections or treating a tumor compressing the RLN, remains the primary focus.