What is the next step in management for a patient with a history of moderately differentiated invasive adenocarcinoma (rectal cancer) status post chemotherapy and radiation, with a new 1.2cm lesion in the presacral space concerning for recurrent disease?

Management of Suspected Recurrent Rectal Cancer in the Presacral Space

For a patient with history of rectal cancer and a new 1.2cm lesion in the presacral space concerning for recurrence, the next step should be a biopsy of the lesion to confirm recurrence, followed by preoperative radiotherapy with or without chemotherapy if radiotherapy was not given during initial treatment, with subsequent surgical resection 4-8 weeks after radiotherapy completion. 1

Diagnostic Confirmation

1. Biopsy confirmation is essential:

   • The suspicious lesion in the presacral space requires histological confirmation before initiating treatment
   • Although imaging findings (PET showing intense FDG uptake, MRI showing a new 1.2cm lesion) strongly suggest recurrence, biopsy remains the standard to confirm diagnosis 1
   • The biopsy should be performed via CT-guidance for precise sampling of the presacral lesion

2. Imaging correlation:

   • The current imaging findings are highly suggestive of recurrence:
     • PET: Intense FDG uptake in the presacral region
     • MRI: New 1.2cm lesion in the presacral space at the rectal resection bed
     • CT CAP: No evidence of distant metastatic disease
   • This pattern of findings is typical for local recurrence rather than a new primary tumor 2

Treatment Algorithm for Confirmed Recurrence

1. If radiotherapy was not given during initial treatment:

   • Preoperative radiotherapy with or without concurrent chemotherapy is strongly recommended (Level II, A evidence) 1
   • Standard regimen: 50 Gy in 1.8-2.0 Gy fractions with concurrent 5-FU-based chemotherapy
   • Surgical resection should be performed 4-8 weeks after completion of radiotherapy 1

2. If radiotherapy was previously given:

   • Surgical resection is the primary treatment option
   • Consider re-irradiation in selected cases with careful attention to cumulative dose constraints
   • Systemic therapy may be considered before surgery in selected cases

3. Surgical approach:

   • Attempt radical surgical resection with curative intent
   • The goal should be complete resection with negative margins
   • The specific surgical approach will depend on the extent of disease and previous surgery

Important Considerations and Caveats

1. Timing of intervention:

   • Do not delay treatment once recurrence is confirmed, as early intervention improves outcomes
   • The 1.2cm size suggests early recurrence that may be more amenable to successful treatment

2. Multidisciplinary discussion:

   • This case should be discussed in a multidisciplinary tumor board to determine optimal sequencing of therapy
   • Input from surgical oncology, radiation oncology, and medical oncology is crucial

3. Common pitfalls to avoid:

   • Avoid proceeding with treatment without histologic confirmation: While imaging is highly suggestive, biopsy confirmation remains standard practice before initiating treatment for recurrence 2
   • Avoid inadequate preoperative assessment: Complete restaging with CT chest/abdomen/pelvis is necessary to rule out distant metastases before pursuing local therapy
   • Avoid suboptimal surgical planning: Careful preoperative planning with MRI is essential to achieve complete resection

4. Follow-up after treatment:

   • After treatment completion, regular surveillance should include:
     • History and physical examination every 3-6 months for 5 years
     • Annual chest, abdominal, and pelvic CT with contrast for 3 years 1

By following this algorithmic approach with proper diagnostic confirmation followed by appropriate multimodality treatment, the best chance for long-term survival and disease control can be achieved for this patient with suspected rectal cancer recurrence.