The abscopal effect is defined as the systemic regression of distant neoplastic lesions induced by localized treatment. Although the first case reports date back to the beginning of the twentieth century, it remains a very rare event. In recent years, research and reporting on the subject has increased thanks to the development of new immune-checkpoint inhibitors (ICIs) and stereotactic body radiotherapy, as a consequence of molecular and clinical synergism. This work describes an extremely particular presentation of metastatic laryngeal cancer, with mediastinal abdominal nodes and bone progressive disease after PD-1 inhibitor failure, which resulted in reductions of bone pain and abdominal and thoracic lymphadenopathies and an improvement in clinical conditions after treatment with concurrent palliative radiotherapy on the bulky mediastinal node and ICI beyond progression, configuring an important abscopal response.
Keywords: abscopal effect; head and neck squamous cell cancer; nivolumab; radioimmunotherapy; tumor microenvironment.
Laryngeal carcinoma is the most common cancer site of the aerodigestive tract and accounts for 25–30% of all head and neck cancer cases. Multimodality treatment (chemotherapy plus surgery and radiotherapy) is pivotal in localized or locally advanced disease, while immunotherapy is reserved for relapsed and metastatic settings. Nivolumab resulted in median overall survival of 7.5 months, progression-free survival of 2.0 months and an estimated 1-year survival rate of 36%; however, the response rate is very poor, at about 14%. Integrating immunotherapy with radiotherapy may prolong the duration of response and enhance efficacy.