What is the best treatment approach for an 80-year-old woman with recurrent adenoid cystic carcinoma (AdCC) in the masticatory space, previously treated with surgery and radiotherapy, now presenting with a 4.5 cm tumor at the edge of the previously irradiated field and deemed clinically inoperable?

Management of Recurrent Adenoid Cystic Carcinoma in an 80-Year-Old Woman

For an 80-year-old woman with recurrent adenoid cystic carcinoma in the masticatory space that is clinically inoperable, re-irradiation with careful dose planning is the recommended treatment approach, potentially with consideration of systemic therapy for palliation if re-irradiation is not feasible.

Assessment of Recurrent Disease

When evaluating recurrent adenoid cystic carcinoma (AdCC), several factors must be considered:

• Location and extent of recurrence (4.5 cm tumor in masticatory space)
• Previous treatments (surgery and radiotherapy in 2021)
• Patient age and performance status (80 years old)
• Proximity to previously irradiated field (edge of previous field with some dose overlap)
• Operability (deemed clinically inoperable)

Treatment Options for Recurrent AdCC

Re-irradiation Approach

For patients with previous irradiation, as in this case, re-irradiation should be considered if a new course of high-dose RT can be delivered without exceeding estimated dose constraints on organs at risk (OARs) 1. The treatment approach should include:

1. Careful dose planning: Reconstruction of the previous RT dose distribution is essential to determine safe re-irradiation parameters 1
2. Target volume definition: Include macroscopic disease with appropriate margins 1
3. Consideration of radiation modality:
   • High Linear Energy Transfer (LET) radiation such as carbon ions may be more effective against radio-resistant clones selected by first treatment 1
   • Intensity-modulated RT can provide better local tumor control and reduced xerostomia 2

Palliative Approach

If re-irradiation cannot achieve sufficiently high dose or adequate coverage without exceeding dose constraints:

1. Low-dose re-irradiation: May be appropriate for palliation if it can be performed with negligible risk of toxicity 1
2. Systemic therapy: Consider for palliation, especially for high-grade disease 1

Special Considerations for Elderly Patients

Age alone should not preclude aggressive treatment if the patient's performance status allows it. A study of elderly patients with cancer showed that those who received aggressive radiotherapy had better outcomes than those managed less intensively for palliation (median survival 60 months vs. 11 months) 3.

Cautions and Contraindications

1. Carotid artery re-irradiation: Particular caution is warranted as severe, life-threatening complications such as carotid blowout syndrome have been reported 1
2. Cumulative dose to critical structures: The radiation dose previously received by nearby OARs often limits the dose that can be safely delivered 1
3. Metal implants: If present, these can complicate RT delivery by creating artifacts in CT/MRI images 1

Treatment Algorithm

1. First option: Re-irradiation with careful dose planning

   • Reconstruct previous RT dose distribution
   • Define appropriate target volumes
   • Consider advanced RT techniques (IMRT, stereotactic RT)
   • Evaluate feasibility of high-dose re-irradiation without exceeding OAR constraints

2. If high-dose re-irradiation is not feasible:

   • Consider low-dose palliative re-irradiation if it can be done safely
   • Evaluate for systemic therapy options
   • Provide appropriate supportive and palliative care

Prognosis and Follow-up

Despite the aggressive nature of recurrent AdCC, long-term survival is possible. Recent data from 2024 shows that patients with AdCC had better outcomes when treated with surgery and postoperative radiotherapy 4. Although this patient's tumor is deemed inoperable, appropriate radiation therapy may still provide meaningful disease control.

Regular follow-up should include:

• Clinical examinations of the treated area and neck
• Evaluation of cranial nerve function
• Imaging surveillance at regular intervals
• Chest CT yearly for at least 2 years due to high rate of late pulmonary metastases 2

While the prognosis for recurrent AdCC is guarded, appropriate management can provide meaningful disease control and improved quality of life.