RADIATION INDUCED SARCOMAS IN HEAD AND

NECK

ABHISHEK PURI

PROBLEM ISSUES Rarity of radiation induced sarcoma;

incidence less than 1%.

Toutas et al reported 0.02% of bone sarcomas; 0.035% 5 year survivors.

Cumulative probability in pediatric age group; 42% sarcomas in irradiated fields.

Toutas et al. Post irradiation sarcoma. Cancer 1979;43:182-197

CONTROVERSIAL? Radiotherapy regimens seldom described

in literature.

Dose levels NOT clearly established; 55Gy is “cut off”; no sarcomatous transformation below 30 Gy.

LONG LATENCY... Mean period of latency for adults was 13

years 10 months; pediatric was 15 years.

In Retinoblastoma patients; latency was 4 years.

No difference of treatment modality (orthovoltage/ megavoltage).

CAHAN's CRITERIA FOR DIAGNOSIS

1) Microscopic evidence of non malignant nature of initial bone condition.

2) Irradiation must have been given and sarcoma subsequently developed must have arisen in the

area included within radiotherapeutic beam.

Cahan et al. Sarcoma arising in irradiated bone. Cancer 1948: 1:3-29

CAHAN's CRITERIA3) A relatively long, asymptomatic period must

have elapsed after irradiation before clinical appearance of sarcoma. (More than 5 years

cure period).

4) All sarcomas must be proved histologically.

Cahan et al. Sarcoma arising in irradiated bone. Cancer 1948: 1:3-29

PUTATIVE CAUSES Higher frequency of sarcoma for orthovoltage

because of greater absorbtion by bone.

Dose response relationship; risk increasing with dose.

Retinoblastoma patients at higher risk of second malignancies.

Higher rate of p53 mutations as compared to sporadic soft tissue sarcomas.

Nakanishi et al. Mutation of p53 gene in post irradiation sarcoma. Lab Invest 1998, 78:727-733

CURRENT POSSIBLE ETIOLOGY

PATHOLOGIC CONSIDERATIONS FOR H&N SARCOMAS

Extends along anatomical planes; en bloc resection mandatory.

Size involving critical neurovascular structures impacts local control and OS.

High grade destructs locally; neurovascular invasion; higher rate of regional/distant metastasis (lung/bone)

COMMONEST HISTOPATH DIAGNOSIS

Malignant Fibrous Histiocytoma

Osteosarcoma & Chondrosarcoma other reported histologies.

RADIOLOGICAL FINDINGS

Left maxiillary sinus mass with heterogeneousEnhancement on T1W images.

SURVIVAL FOR H&N SARCOMAS

5 year OS ranges between 10 and 30% ; worse than prognosis of sarcomas of similar stage.

Delay of diagnosis; proximity to neurovascular structures; limited treatment options- poor senstivity to chemotherapy.

Robinson E et al. Clinical aspects of post irradiation sarcomas. JNCI 1988;80:233-40

Radiation Induced Sarcomas compared to Sarcomas in Head and Neck arising denovo.

MANAGEMENT OPTIONS

CHEMOTHERAPY Doxorubicin 75mg/m2 & 100 mg/m2 every

4 weeks.

Surgical consolidation considered after downstaging.

Dose intensification protocols for <95% necrosis.

SURGICAL PRINCIPLES General principles of surgical oncology

followed.

Margin negative excision is ideal goal.

Occassionally radical surgery becomes necessary for effective palliation.

ROLE OF RADIATION? Not clearly defined.

Normal tissue tolerance limits delvery of therapeutic dose.

Brachytherapy or intraoperative radiotherapy can be individualised.

CASE REPORT 82 year old man presented with

progressive trismus and swelling left jaw.

Earlier treated with Carcinoma Tonsil 10 years back with local XRT.

Painful expansile lesion in left mandible.No palpable lymphadenopathy.

Underwent composite resection.

HPR reported as

Osteogenic Sarcoma.

*Malignant Spindle Cells. ** Mineralised Tumor Osteoid***Chondroblastic Component

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