What is the treatment and management approach for adenoid cystic carcinoma?

From the Guidelines

The primary treatment for adenoid cystic carcinoma (ACC) is complete surgical resection with clear margins, often followed by adjuvant radiation therapy, as this approach has been shown to improve overall survival (OS) and local control (LC) 1. When managing ACC, it is crucial to balance the oncologic benefit of surgery with the potential morbidity associated with facial nerve resection.

• The decision to resect facial nerve branches should be made cautiously, considering the potential impact on the patient's quality of life.
• According to the ASCO guideline, facial nerve branches should only be resected when this will allow for complete margin clearance or when the nerve is grossly infiltrated or encased by malignancy 1.
• In cases where preoperative facial nerve function is normal, preserving the facial nerve is recommended, especially for early-stage low- and intermediate-grade parotid cancers, as this approach has been shown to result in excellent disease control 1.
• Adjuvant radiation therapy is often recommended, even with negative margins, due to ACC's propensity for perineural invasion and local recurrence.
• The use of adjuvant radiation therapy has been shown to increase local control and trend toward better overall survival in patients with ACC 1.
• Systemic therapy, including platinum-based chemotherapy regimens or targeted therapies like lenvatinib, may be considered for recurrent or metastatic disease, although its efficacy is limited.
• Long-term surveillance is essential, with follow-up recommended for at least 15 years, due to the slow growth and late recurrences characteristic of ACC.
• Management of ACC should be coordinated by a multidisciplinary team, given the complex nature of this rare cancer and its tendency to affect critical structures in the head and neck region.

From the Research

Treatment and Management Approach for Adenoid Cystic Carcinoma

• The primary treatment for head and neck adenoid cystic carcinoma (ACC) is surgery, but in cases where surgery is not possible due to the tumor's location or spread, other treatment options are considered 2, 3.
• Definitive proton radiation therapy and concurrent cisplatin have been shown to be a viable treatment option for select patients with unresectable head and neck ACC, with preliminary results suggesting good local disease control and manageable toxicity 2.
• Chemoradiotherapy (CRT) with weekly carboplatin and paclitaxel has also been explored as an organ-sparing treatment modality for patients with locally advanced laryngeal ACC, with promising results in terms of local regional control and functional larynx preservation 4.
• Adjuvant radiotherapy is often used in conjunction with surgery to improve treatment outcomes, and proton therapy has been shown to provide excellent disease control for ACC of the head and neck with acceptable toxicity 5.
• The treatment approach for recurrent or metastatic ACC is not personalized and is typically limited to cytotoxic agents and VEGFR inhibitors, which can produce modest responses and significant toxicity 6.
• Molecular drivers, such as NOTCH1, have emerged as potential therapeutic targets for ACC, and proteogenomic studies have revealed two molecular subtypes of ACC with distinct disease biology and prognosis, which may guide the development of biomarkers for patient selection and new therapies development 6.

Prognostic Factors and Outcomes

• Intracranial extension and gross residual tumor have been identified as factors associated with worse local-regional control rates in patients with ACC treated with proton therapy 5.
• The 5-year local-regional control, disease-free survival, cause-specific survival, and overall survival rates for patients with ACC treated with proton therapy have been reported to be 88%, 85%, 89%, and 89%, respectively 5.
• The cumulative incidence of clinically significant grade ≥3 toxicity has been reported to be 15% at 5 years, and the crude incidence at the most recent follow-up was 23% 5.

Future Directions

• Further research is needed to develop personalized treatment approaches for recurrent or metastatic ACC, and to explore the potential of molecular drivers as therapeutic targets 6.
• The use of proton therapy and other advanced radiation techniques may continue to play an important role in the treatment of ACC, particularly for patients with unresectable or locally advanced disease 2, 5.