9 - Cancer and Reconstruction

Question 1

Diagnostics aids in dysplastic lesions

Answer 1

• Chemical
  
  • Lugols iodine
    
    • Sugar attached to iodine
    • Metabolically active areas will use up sugar and appear white
  • Toluidine blue
    
    • Stains acidic tissue components
    • Affinity for tissues rich in DNA and RNA
    • Poor PPV
• Light based detection
  
  • Vizilite (Chemiluminescence)
    
    • Acetic acid mouthwash - to remove glycoprotein barrier
    • Blue light
      
      • Normal tissue - Blue colour
      • Abnormal tissue with high nucleus to cytoplasmic ratio - Reflects light back and appears white
  • Immunofluorescence
    
    • Velscope
      
      • Blue light shown into the mouth
      • Normal tissue and excites the tissue causing it to fluoresce
      • Abnormal tissue appear black
    • Tissue fluorescence spectroscopy
      
      • Small optical fibre produces various excitation wavelengths and maps out area of dysplasia
      • Limited to small lesions

Question 2

Free Flaps

Answer 2

Question 3

Indications for pre radiotherapy extractions

Answer 3

• Ben David 2007
  
  • Teeth with unrestorable caries
  • Caries extending to gingival margins
  • Large compromised restorations with pocketing >5mm
  • Periodontal disease
    
    • Mobile teeth
    • Significant pocketing
    • Advanced recession or furcation involvement
  • Severe erosion or abrasion
  • Non functional teeth
  • Primary closure and alveoloplasty

Question 4

Melanoma Dermatoscopy

Answer 4

• Dermatoscopy Clinical Findings
  
  • Irregular borders
  • Pseudopods
  • Radial streaming
  • Scar like depigmentation
  • Heterogeneity in colour
  • Irregular vascularity

Question 5

Melanoma Management

Answer 5

• Sentinel lymph node biopsy
  
  • MSLT II Trial
    
    • Most patients only have one small positive node (~80%)
    • No difference between SLB and Completion neck dissection
      
      • CND slightly improves 3 yr Disease free survival but not Melanoma specific survival
      • If melanoma has metastasized to more than one node - Prognosis is not changed by doing a neck dissection
    • AJCC - Recommends ND in up to Stage III disease

Question 6

Melanoma Pathophysiology

Answer 6

• Radial Growth Phase
  
  • Lower risk phase
  • Nodular melanoma does not have this phase
    ​
• Vertical Growth Phase
  
  • Risk based phase
  • Based on Breslow Depth
    ​
• Mutations
  
  • BRAF
  • cKIT - Mucosal melanoma

Question 7

Melanoma Risk Factors

Answer 7

• Risk Factors
  
  • Epidemiology
    
    • Male
    • Age > 50
  • History
    
    • Family Hx
    • Personal Hx of melanoma or other skin cancer
    • Immunosuppression
  • Genetics
    
    • Fitzpatrick I or II
    • CDKN2A mutation - Involved in Rb
    • Syndromes
      
      • Dysplastic naevus syndrome
      • Basal cell naevus syndrome
      • Xeroderma pigmentosum

Question 8

Melanoma Staging

Answer 8

• Breslow Depth
  Used by AJCC as a prognostic factor in staging melanoma
  Measurement of the depth of invasion of melanoma
  
  • Stage I - <1mm
  • Stage II - 1-2mm
  • Stage III - 2.1 - 4mm
  • Stage IV - >4mm
• Clarks Level
  Describes the depth of the melanoma based on anatomical regions
  
  • Level I - Epidermis
  • Level II - Papillary dermis
  • Level III - Papillary and Reticular dermis interface
  • Level IV - Reticular dermis
  • Level V - Subcut fat

Question 9

Melanoma Types

Answer 9

• Melanoma Types
  
  • Superficial spreading
    
    • Most common - 70%
    • Irregular pigmented macule
    • Grows radially then vertically
  • Nodular - 15%
    
    • Aggressive tumor
    • Invasive vertical growth pattern
    • 50% hypomelanotic
  • Acral lentiginous 5%
    
    • Palms, sole, nail beds
    • Tends to occur in dark skinned people
  • Desmoplastic
    
    • Rare
    • Appears like a scar
  • Mucosal melanoma
    
    • Very rare
    • Aggressive with poor prognosis

Question 10

Melanoma Workup and Staging

Answer 10

• Workup
  
  • Biopsy
    
    • Excisional biopsy with a 2-3mm
    • Incisonal biopsy if anatomically challenging or large size
    • Incisional biopsy where there is a low index of suspicion
  • Immunohistochemistry staining
    
    • HMB45
    • S-100
    • Melan-A
      ​
• Staging
  
  • Cutaneous
    
    • T1-4 based on Breslow depth
      
      • b - Ulceration
  • Mucosal
    
    • T3 - Starting point for mucosal melanoma
    • T4 - Invasion into adjacent tissue

Question 11

Multistage Carcinogenesis Steps

Answer 11

• Initiation
• Promotion
• Conversion
• Progression
• Initiation
  
  • Initial damage to DNA by a carcinogen
  • Causes either the activation of a Proto-oncogene or inactivation of a Tumor-suppressor gene
    ​
• Promotion
  
  • Selective clonal expansion of “initiated” cell
  • Tumor promotors are generally not mutagenic or carcinogenic. They act by reducing the latency period between mitosis
    Agents capacble of both tumor initiation and promotion are known as complete carcinogens
    ​
• Conversion
  
  • Transformation of a pre-neoplastic cell into one that expresses the malignant phenotype.
    ​
• Progression
  
  • Expression of malignant phenotype and invading into adjacent tissue and metastasising

Question 12

OPSCC Epidemiology, Risk Factors & Pathophysiology

Answer 12

• Epidemiology
  
  • M:F - 3:1
  • Younger median age at diagnosis
  • HPV responsibility for ~70% of OPSCC
    ​
• Risk Factors
  
  • Male
  • High SES
  • Caucasians > Blacks
  • Increased sexual partners
  • <60 yrs of age
    ​
• Pathophysiology
  
  • Preference for Oro pharynx theories
    
    • Tonsillar crypts trap saliva - more time for HPV to access basement cells
    • Transitional epithelium like cervix
  • HPV exerts its actions via inactivation of:
    
    • E6 Protein - downregulates p53
      
      • As a result of p53 being downregulated
        p16 is upregulated
      • p16 is used as a surrogate marker of HPV infection
    • E7 Protein - downregulates Rb

Question 13

OPSCC Prognosis and Management

Answer 13

• Prognosis
  p16 +ve OPSCC tends to have a better prognosis compared to p16-ve SCC
  
  • HPV +ve tumours habour fewer or different genetic mutations
  • More sensitive to radiation
    
    • Likely due to intact apoptotic response
  • Absence of field cancerisation
  • Immunologic response may play a role due to recognition of viral antigens
  • Younger age group
    
    • Better performance status
    • Fewer comorbidities
      ​
• Management
  
  • (T1 or T2) + N0
    
    • Single modality - Radiotherapy or Surgery
      ​Surgery preferred due to morbidity
      
      • Indications
        
        • NCCN 2016 guidelines
          
          • Preferred over XRT alone in localised resectable disease
        • Fat plane present between tumour and pharynx
        • Bulky disease
        • Better disease control and lower locoregional recurrence rate
        • Less morbidity especially swallowing
        • Neck dissection provides prognostic information that directs adjuvant treatment
      • Surgical modalities
        
        • CO2 laser with direct laryngoscopy
          
          • Tumor randomly cut out to reduce bulk
        • TORS (Transoral robotic surgery)
          
          • Limited to T1 and T2 tumors
          • Tumor resected systematically
        • Lip split mandibulotomy
          
          • Open surgery
  • More advanced stage
    
    • Multi-modal therapy
      
      • Chemoradiotherapy
      • consideration of a neck dissection
        ​
• Survival
  
  • Stage I - 90%
  • Stage II - 70%
  • Stage III - 50%

Question 14

Alberta Reconstructive Technique

Answer 14

Alberta Reconstructive Technique

• Surgical Technique
  ​Two stage surgical procedure
  
  • Stage I
    
    • VSP planned
    • Fibula exposed
    • Implants inserted into fibula with guides prior to osteotomy
    • Occlusal template used intra-orally to ensure fibula segments are aligned properly prior to fixation onto plate
    • Skin paddle used to cover implants
    • Buried for 6 months
  • Stage II
    
    • Exposure of implants and soft tissue augmentation
      ​
• Differences betwen ART and Rohner
  
  • ART - does not have keratinised epithelium
  • ART can be considered a one stage procedure
  • ART has shorter time between VSP planning and resection of tumor
    ​
• Outcomes
  
  • Cheaper than standard technique
    Money saved on multiple review appt and pros cost due to improper placement of implants
  • 96% of implants utilized in ART
    83% of implants utilized in Standard Technique
  • Shorter time to dental rehab with ART

Question 15

Rohner Technique

Answer 15

Rohner 2003

• Surgical Technique
  Two surgical stage procedure
  
  • Stage I
    
    • Implants inserted into fibula
    • Impressions taken at this stage
    • STSG onto periosteum with Goretex membrane over STSG
    • 4-6 week healing prior to free flap harvest
    • Anticoagulation given between the two procedures
    • Prosthesis constructed prior to the second procedure
  • Stage II
    
    • Cutting guide used to osteotomize fibula into predetermined segments
    • Prosthesis used as guide for stabilisation of fibula segments
      Prosthesis placed onto implants and secured in IMF
      ​
  • 95% Success rate of implants

Question 16

SM-ART Technique

Answer 16

Sydney Modified - Alberta Reconstructive Technique
Surgical Technique

• ​Two stage surgical procedure
  
  • Stage I
    
    • VSP planned
    • Fibula exposed
    • Implants inserted into fibula with guides prior to osteotomy
    • Occlusal template used intra-orally to ensure fibula segments are aligned properly prior to fixation onto plate
    • Custom recon plate used
    • STSG taken. Silicone sheet used to cover STSG
    • Skin paddle used to cover implants
    • Buried for 6 months
  • Stage II
    
    • Exposure of implants and soft tissue augmentation
    • Skin paddle divided in the middle
      Sutured onto the edges of the integrated STSG to form a new buccal and lingual sulcus
      ​
• Difference between SMART and ART
  
  • STSG taken
    Keratinised epithelium over implant
  • Custom recon plate used

Question 17

Zygomatic implant perforated flap

Answer 17

Zygomatic implant perforated flap
One stage procedure

• Surgical Technique
  
  • Resection of tumor
  • Quad zygomas placed free hand
  • Impressions taken immediately post implant placement
  • Zygomatic implants perforate the soft tissue flap
    
    • Clear plastic placed under healing abutments

Question 18

Oral premalignant disorders

Answer 18

• WHO 2017
  
  • Leukoplakia
  • Proliferative verrucous leukoplakia
  • Erythroleukoplakia
  • Erythroplakia
  • Smokers keratosis
  • Submucous fibrosis
  • Chronic hyperplastic candidiasis
  • Syphillitic glossitis
  • Acitnic cheilitis
  • Discoid lupus erythematosis
  • Genetic
    
    • Fanconic syndrome
    • Dyskeratosis congentia
    • Xeroderma pigmentosum
    • Plummer Vinson syndrome
    • Epidemolysis bullosa
    • Graft vs Host disease

Question 19

Bone Graft - Non vascularized vs Vascularized

Answer 19

• Pogrel 1997
  
  • Vascularized vs Non-vascularized bone grafts
  • Non vascularized bone graft
    
    • <6cm : 17% failure rate
    • >12cm : 75% failure rate
      ​

Question 20

Defects - Maxilla Classification

Answer 20

• Classification can be broken down into defect based classification and rehabilitation based classification
• Defect based classification
  
  • Browns 2010
    
    • Vertical/Esthetic
      
      • I - Alveolus
      • II - Alveolus + Infrastructure maxilla
      • III - Alveolus + Orbital floor
      • IV - Alveolus + Orbital floor + Orbital contents
      • V - Orbitomaxillary defect
      • VI - Nasomaxillary defect
    • Horizontal/Functional
      
      • A - Palatal defect only
      • B - Less than 1/2 unilateral
      • C - Anterior defect, less than 1/2
      • D - Greater than 1/2
        ​
  • Cordeiro 2000
    Based on the maxilla having 6 walls
    
    • I - Limited maxillectomy - 1 or 2 walls resected
    • II - Subtotal maxillectomy - Resection of the lower 5 walls maxillary arch, palate, ant and lateral walls with preservation of orbital floor
    • III - Total maxillectomy - Resection of all 6 walls of the maxilla
      
      • a - Preservation of orbital contents
      • b - Exenteration of orbital contents
    • IV - Orbitomaxillecomy - Resection of the upper 5 walls with preservation of the palate
      ​
• Rehabilitation Classifications
  Based on whether obturator is able to be supported
  • Okay Classification
    
    • Ia - Defects that involve hard palatel but not the tooth-bearing alveolus
    • Ib - Defects that involve any part of the maxillary alveolus and dentition posterior to the canines or involving the pre-maxilla
    • II - Defects that involve any portion of the tooth-bearing alveolus but include only 1 canine
      Anterior palatectomy that involved less than one half of the palate
    • III - Defects that involved any portion of tooth-bearing maxillary alveolus and includes both canines, total palatectomy and anterior transverse palatectomy that involve >50% of the palate surface
    • Subclass
      
      • f - Defects including inferior orbital rim
      • z - Defects involving the zygoma
        ​
  • Ohngren’s Line
    
    • Line that connects from the ipsilateral medial canthus to the ipsilateral angle of the mandible
      
      • Suprastructure - Above Ohngren’s line
        ​Lesions arising from above this line carry a worse prognosis
      • Infrastructure - Below Ohngren’s line
        Lesions below this line can be obturated

Question 21

Defects - Mandible Classification

Answer 21

• Browns Classification
  
  • I - Lateral not including canine or condyle​
  • II - Hemimandibulectomy - Including ipsilateral canine
  • III - Anterior defect - Bilateral canines but not angles
  • IV - Extensive anterior defect - Bilateral canines and bilateral angles
  • c - Denotes the resection of a condyle
• Urken’s Classification
  Different permutations used to describe defect
  
  • Bone
    
    • C - Condyle
    • R - Ramus & Angle
    • B - Body
    • S - Symphysis
      
      • SH - Hemi-symphysis
  • Soft Tissue
    
    • Mucosa
      
      • L - Labial
      • B - Buccal
      • SP - Soft Palate
      • FOM - Floor of Mouth
    • T - Tongue
    • C - Cutaneous
  • Neurological
    
    • IA - Inferior Alveolar
    • L - Lingual
    • H - Hypoglossal
    • F - Facial
• Jewer’s Classification
  Different permutations of HCL is used to described the defect
  
  • H - Hemi - Lateral defect including the condyle but not including canines
  • L - Lateral - Lateral defect not including condyle or canine
  • C - Central - Central defect including bilateral canines