Transient neurological adverse effects following low dose radiation therapy for early stage testicular seminoma

Radiation-induced neuropathy in cancer survivors

Radiation-induced peripheral neuropathy is a chronic handicap, frightening because progressive and usually irreversible, usually appearing several years after radiotherapy. Its occurrence is rare but increasing with improved long-term cancer survival. The pathophysiological mechanisms are not yet fully understood. Nerve compression by indirect extensive radiation-induced fibrosis plays a central role, in addition to direct injury to nerves through axonal damage and demyelination and injury to blood vessels by ischaemia following capillary network failure. There is great clinical heterogeneity in neurological presentation since various anatomic sites are irradiated. The well-known frequent form is radiation-induced brachial plexopathy (RIBP) following breast cancer irradiation, while tumour recurrence is easier to discount today with the help of magnetic resonance imaging and positron emission tomography. RIBP incidence is in accordance with the irradiation technique, and ranges from 66% RIBP with 60Gy in 5Gy fractions in the 1960s to less than 1% with 50Gy in 2Gy fractions today. Whereas a link with previous radiotherapy is forgotten or difficult to establish, this has recently been facilitated by a posteriori conformal radiotherapy with 3D-dosimetric reconstitution: lumbosacral radiculo-plexopathy following testicular seminoma or Hodgkin's disease misdiagnosed as amyotrophic lateral sclerosis. Promising treatments via the antioxidant pathway for radiation-induced fibrosis suggest a way to improve the everyday quality of life of these long-term cancer survivors.

Late radiation injury to peripheral nerves

Although the peripheral nerve has often been considered as radioresistant, clinical practice demonstrates the occurrence of radiation-induced peripheral neuropathies. Because these complications appear late, usually several years after the course of radiotherapy, their occurrence is explained by improvement in the prognosis of several cancers. Their physiopathology is not fully understood. Compression by radio-induced fibrosis probably plays a central role but direct injury to nerves and blood vessels is probably also involved. The most frequent and best known form of postradiation neuropathy is brachial plexopathy, which may follow irradiation for breast cancer. Recent reports demonstrate that postradiation neuropathies show a great heterogeneity, particularly in the anatomical sites, but also in the clinical, electrophysiological, and neuroimaging features. The link with radiotherapy may be difficult for the clinician to establish. Patients with radiation-induced lumbosacral radiculoplexopathy may be misdiagnosed with amyotrophic lateral sclerosis as they often present with pure lower motor neuron syndrome, or with leptomeningeal metastases since nodular MRI enhancement of the nerve roots of the cauda equina and increased CSF protein content can be observed. From a pathophysiological perspective, radiation-induced neuropathy offers an interesting model for deciphering the mechanisms of peripheral neuropathies due to environmental factors. Recent developments show promising strategies for the prevention and treatment of these complications, which have a considerable impact on a patient's quality of life.

Neurological Adverse Effects after Radiation Therapy for Stage II Seminoma

We report 3 cases of patients with testicular cancer and stage II seminoma who developed neurological symptoms with bilateral leg weakness about 4 to 9 months after radiation therapy (RT). They all received RT to the para-aortic lymph nodes with a total dose of 40 Gy (36 Gy + 4 Gy as a boost against the tumour bed) with a conventional fractionation of 2 Gy/day, 5 days per week. RT was applied as hockey-stick portals, also called L-fields. In 2 cases, the symptoms fully resolved. Therapeutic irradiation can cause significant injury to the peripheral nerves of the lumbosacral plexus and/or to the spinal cord. RT is believed to produce plexus injury by both direct toxic effects and secondary microinfarction of the nerves, but the exact pathophysiology of RT-induced injury is unclear. Since reported studies of radiation-induced neurological adverse effects are limited, it is difficult to estimate their frequency and outcome. The treatment of neurological symptoms due to RT is symptomatic.

[Radiation-induced neuropathies: collateral damage of improved cancer prognosis]

INTRODUCTION

Because of the improvement of cancer prognosis, long-term damages of treatments become a medical and public health problem. Among the iatrogenic complications, neurological impairment is crucial to consider since motor disability and pain have a considerable impact on quality of life of long cancer survivors. However, radiation-induced neuropathies have not been the focus of great attention. The objective of this paper is to provide an updated review about the radiation-induced lesions of the peripheral nerve system.

STATE OF THE ART

Radiation-induced neuropathies are characterized by their heterogeneity in both symptoms and disease course. Signs and symptoms depend on the affected structures of the peripheral nerve system (nerve roots, nerve plexus or nerve trunks). Early-onset complications are often transient and late complications are usually progressive and associated with a poor prognosis. The most frequent and well known is delayed radiation-induced brachial plexopathy, which may follow breast cancer irradiation. Radiation-induced lumbosacral radiculoplexopathy is characterized by pure or predominant lower motor neuron signs. They can be misdiagnosed, confused with amyotrophic lateral sclerosis (ALS) or with leptomeningeal metastases since nodular MRI enhancement of the nerve roots of the cauda equina and increased cerebrospinal fluid protein content can be observed. In the absence of specific markers of the link with radiotherapy, the diagnosis of post-radiation neuropathy may be difficult. Recently, a posteriori conformal radiotherapy with 3D dosimetric reconstitution has been developed to link a precise anatomical site to unexpected excess irradiation.

PERSPECTIVES AND CONCLUSION

The importance of early diagnosis of radiation-induced neuropathies is underscored by the emergence of new disease-modifying treatments. Although the pathophysiology is not fully understood, it is already possible to target radiation-induced fibrosis but also associated factors such as ischemia, oxidative stress and inflammation. A phase III trial evaluating the association of pentoxifylline, tocopherol and clodronate (PENTOCLO, NCT01291433) in radiation-induced neuropathies is now recruiting.

Radiotherapy-induced lumbosacral plexopathy in a patient with cervical cancer: a case report and literature review

Radiotherapy-induced lumbosacral plexopathy in cervical cancer treatment is a very rare, but extremely serious complication. The clinical course is associated with severe bilateral lower leg pain, reduced sensation, different degrees of weakness, paresis or paralysis, and sometimes also urinary or fecal incontinence. Patient quality of life becomes significantly deteriorated. Escalating neurological disorders may make self-sufficient functioning impossible. Neurological symptoms, most often irreversible, may develop at different times after irradiation, even after more than 30 years. We present a case of neurological toxicity in a patient successfully treated for cervical cancer with pelvis and para-aortic lymph node irradiation and weekly cisplatin. Neurological symptoms developed a few weeks after completion of external irradiation, were gradually escalating and resulted in complete immobilization of the woman. We underline the significance of long-term, systematic physiotherapy and pharmacological therapy which has resulted in significant improvement of motion efficiency. The literature review concerns the questions of frequency, clinical course and mechanisms of radiation-induced plexopathy.

Neurotoxicity of radiation therapy

Direct or incidental exposure of the nervous system to therapeutic irradiation carries the risk of symptomatic neurologic injury. Central nervous system toxicity from radiation includes focal cerebral necrosis, neurocognitive deficits, and less commonly cerebrovascular disease, myelopathy, or the occurrence of a radiation-induced neoplasm. Brachial or lumbosacral plexopathy are the most common syndromes of radiation toxicity affecting the peripheral nervous system. This article focuses on the clinical features, diagnosis, and management options for patients with radiation neurotoxicity.

Observational study of prevalence of long-term Raynaud-like phenomena and neurological side effects in testicular cancer survivors

Background

Sensory neuropathy (paresthesias), tinnitus, hearing impairment, and Raynaud phenomena are side effects of cisplatin-based chemotherapy used to treat testicular cancer patients. We assessed the long-term occurrence of these side effects among testicular cancer survivors according to the treatment they received.

Methods

A total of 1814 men who were treated for unilateral testicular cancer in Norway during 1980–1994 were invited to participate in a national multicenter follow-up survey conducted during 1998–2002. The men were allocated to six groups according to the treatment they had received. Self-reported symptoms were assessed by a mailed questionnaire that included the Scale for Chemotherapy-Induced Neurotoxicity. A total of 1409 participants who responded to the questionnaire and/or underwent audiometry were assessable in this study. Respondents to the questionnaire (n = 1402) scored the relevant symptoms according to how troubled they were by each (not at all, a little, quite a bit, or very much). Hearing impairment was objectively assessed by audiometry at 4000 Hz in 755 men (seven of whom did not respond to the questionnaire). Group comparisons of symptom assessments were performed with χ² or Kruskal–Wallis tests. Associations between relevant factors and self-reported symptoms or hearing impairment measured by audiometry were assessed using proportional odds ordinal logistic regression models and linear regression models, respectively. All statistical tests were two-sided.

Results

The median follow-up for the 1409 assessable men was 10.7 years (range = 4–21 years). All chemotherapy groups had statistically significantly higher odds for increasing severity of all assessed symptoms and inferior audiometric results compared with men who did not receive chemotherapy. Among chemotherapy-treated men, 39% (95% confidence interval [CI] = 35% to 43%) reported Raynaud-like phenomena (defined as white or cold hands or fingers [or feet or toes] on cold exposure), 29% (95% CI = 25% to 33%) reported paresthesias in the hands or feet, 21% (95% CI = 18% to 25%) reported hearing impairment, and 22% (95% CI = 19% to 26%) reported tinnitus as major symptoms troubling them quite a bit or very much. Hearing impairment (odds ratio [OR] = 5.3, 95% CI = 3.0 to 9.2) and tinnitus (OR = 7.1, 95% CI = 4.1 to 12.4) were particularly common in the dose-intensive chemotherapy group compared with the no chemotherapy group. Men who were treated with radiotherapy had higher odds of self-reported paresthesias in feet compared with those not treated with radiotherapy (OR = 1.5, 95% CI = 1.01 to 2.1, P = .04).

Conclusion

Long-term survivors of testicular cancer who were treated with cisplatin-based chemotherapy were more often troubled by dose-dependent neurological side effects and Raynaud-like phenomena compared with those who were not treated with chemotherapy.