Proton Beam Therapy for Bronchogenic Adenoid Cystic Carcinoma: Dosimetry, Toxicities, and Outcomes

Dose-Escalated Radiotherapy for Primary Tracheobronchial Adenoid Cystic Carcinoma

Primary tracheobronchial adenoid cystic carcinoma (ACC) is a rare malignancy, so the optimal radiotherapy (RT) dose remains unestablished. We aimed to evaluate the effectiveness of dose-escalated RT for primary tracheobronchial ACC. We retrospectively reviewed 48 patients who had undergone definitive or postoperative RT. Patients classified into the low- and high-dose groups received RT doses <70.0 and ≥70.0 Gy in EQD2, respectively. The primary endpoint was freedom from local progression (FFLP) and overall survival (OS). Throughout the follow-up period, seven patients (14.6%) experienced local progression, while 31 (64.6%) exhibited distant metastasis, most commonly in the lungs. In total, the 5-year FFLP and OS rates were 85.7 and 84.7%, respectively. Multivariate analysis revealed that regional lymph node metastasis at diagnosis and receipt of definitive RT were associated with poorer OS. In the subgroup analysis, the definitive RT group had a 5-year FFLP rate of 33.3 and 78.2% in the low- and high-dose groups (p = 0.065), whereas 5-year OS rates were 66.7 and 79.0%, respectively (p = 0.022). Four patients (8.3%) experienced Grade 3 toxicity with tracheal or main bronchus stenosis. Dose-escalated RT with conventional fractionation may be effective in patients with tracheobronchial ACC, especially for a definitive aim.

Long-term follow-up of unresectable adenoid cystic carcinoma of the trachea and bronchus treated with high-dose proton beam therapy: A report of two cases

Adenoid cystic carcinoma (ACC) of the trachea is a rare disease that is slow growing and has a risk of distant metastasis. The standard treatment for ACC of the trachea is surgery, but this tumor is often unresectable. In definitive radiotherapy using photons for unresectable ACC of the trachea, it is sometimes difficult to deliver a sufficient dose to the target without exceeding the tolerable dose to the surrounding normal tissues. Here, we report two cases of ACC of the trachea that received a high dose (74 Gy [relative biological effectiveness]) of proton beam therapy and achieved long-term survival.

Subglottotracheal Adenoid Cystic Carcinoma in a 16-Year-Old Female-A Case Report

Cystic adenoid carcinoma (ACC) is a rare malignant epithelial tumor arising from exocrine glands and accounts for only 1% of head and neck cancers. ACCs are common in the fifth and sixth decades of life, predominantly in women, and characterized by slow progression, local aggression, recurrence, and high metastasis. Subglottotracheal ACC is a rare tumor in the pediatric population, with only a few cases reported in the literature. We present a case of a 16-year-old female who was diagnosed with ACC in the subglottic and tracheal region. The patient presented with respiratory failure but without a history of dysphonia, dyspnea, stridor, or dysphagia. The diagnosis was confirmed by a biopsy, and subsequent imaging studies showed a large tumor involving the subglottic and tracheal region. The therapeutic management of this patient has been challenging due to the rarity of this tumor in the pediatric population and the potential long-term complications associated with tumor recurrence and psychological impact. This case highlights the diagnostic and therapeutic challenges in the management of subglottotracheal ACC in children and the importance of a multidisciplinary approach to optimize patient outcomes.

Definitive carbon ion radiotherapy for tracheobronchial adenoid cystic carcinoma: a preliminary report

Background

Tracheobronchial adenoid cystic carcinoma (TACC) is a rare tumour. About one-third of patients miss their chance of surgery or complete resection as it is mostly detected in the advanced stage; hence, photon radiotherapy (RT) is used. However, the outcomes of photon RT remain unsatisfactory. Carbon ion radiotherapy (CIRT) is thought to improve the therapeutic gain ratio; however, the outcomes of CIRT in TACC are unclear. Therefore, we aimed to assess the effects and toxicities of CIRT in patients with TACC.

Methods

The inclusion criteria were as follows: 1) age 18–80 years; 2) Eastern Cooperative Oncology Group Performance Status 0–2; 3) histologically confirmed TACC; 4) stage III–IV disease; 5) visible primary tumour; and 6) no previous RT history. The planned prescription doses of CIRT were 66–72.6 GyE/22–23 fractions. The rates of overall survival (OS), local control (LC), and progression-free survival (PFS) were calculated using the Kaplan-Meier method. Treatment-induced toxicities and tumour response were scored according to the Common Terminology Criteria for Adverse Events and Response Evaluation Criteria in Solid Tumors, respectively.

Results

Eighteen patients with a median age of 48 (range 30–73) years were enrolled. The median follow-up time was 20.7 (range 5.8–44.1) months. The overall response rate was 88.2%. Five patients developed lung metastasis after 12.2–41.0 months and one of them experienced local recurrence at 31.9 months after CIRT. The rates of 2-year OS, LC, and PFS were 100, 100, and 61.4%, respectively. Except for one patient who experienced grade 4 tracheal stenosis, which was relieved after stent implantation, no other ≥3 grade toxicities were observed.

Conclusions

CIRT might be safe and effective in the management of TACC based on a short observation period. Further studies with more cases and longer observation are warranted.