What are the indications for a hemi‑mandibulectomy in oral cavity cancer?

Indications for Hemi-Mandibulectomy in Oral Cavity Cancer

Segmental (hemi) mandibulectomy is indicated when oral cavity tumors grossly involve the mandibular periosteum (determined by tumor fixation to the mandible) or show direct tumor involvement of bone on preoperative imaging or at the time of operation 1, 2.

Clinical Decision Algorithm

The extent of mandibular resection follows a stepwise approach based on tumor-bone relationship:

Marginal Mandibulectomy (Rim Resection)

• Tumors involving or adherent to mandibular periosteum without bone invasion
• Partial, horizontal, or sagittal resection preserving mandibular continuity
• Appropriate when tumor abuts but does not invade bone 1, 2

Segmental Mandibulectomy (Hemimandibulectomy)

Perform when ANY of the following are present:

1. Gross periosteal involvement - tumor is fixed to the mandible on clinical examination 1, 2

2. Radiographic bone invasion - preoperative imaging (CT/MRI) demonstrates direct tumor involvement of mandibular bone 1, 2

3. Intraoperative findings - direct bone involvement discovered during surgery 1, 2

4. Inferior alveolar nerve invasion - though uncommon (5% of infiltrated mandibles), this represents direct bone involvement 3

Critical Assessment Points

Preoperative evaluation must include:

• Clinical examination for tumor fixation to mandible
• Panorex and cross-sectional imaging (CT with bone windows preferred)
• Careful palpation to distinguish periosteal adherence from bone invasion 1

Intraoperative decision-making:

• The final extent of mandibular resection is determined by clinical assessment AND intraoperative findings
• Frozen section evaluation of bone margins should be considered
• The degree of involvement guides whether marginal versus segmental resection is performed 1, 2

Important Caveats

Avoid over-resection: Historical data shows that in nearly 55% of mandibles resected, tumor was not actually present in the bone 3. This emphasizes the need for accurate preoperative imaging and judicious intraoperative assessment rather than reflexive segmental resection.

Oncologic adequacy: The goal is achieving tumor-free margins (≥5 mm clear margin) 2. Segmental mandibulectomy should not be performed simply for proximity—only when there is actual periosteal fixation or bone invasion.

Reconstruction planning: When segmental resection is performed, immediate reconstruction with vascularized bone flap (typically fibula) should be planned to reduce postoperative complications and improve functional outcomes 3.

The decision between marginal and segmental mandibulectomy ultimately depends on whether the tumor can be completely excised with adequate margins while preserving mandibular continuity. When in doubt intraoperatively about the adequacy of a marginal resection, proceed to segmental resection to ensure oncologic clearance 1, 2.