A BOOST TECHNIQUE FOR IRRADIATION OF MALIGNANT CANINE NASAL TUMORS

Eighteen dogs with malignant nasal cavity tumors were treated with radiation therapy, including a boost technique. Three 3:0 Gy boost doses were added to a treatment protocol consisting of sixteen 3.0 Gy daily fractions, bringing the total dose to 57 Gy. This boost technique was implemented without an associated increase in overall treatment time by giving the boost doses on a twice-a-day basis. Boost doses were given during the first half of the radiation therapy period. The treatment was completed as planned in 16 of the 18 dogs; two dogs received lower doses (51 and 54 Gy). Median survival was 177 days, poorer than in some other reported studies of nasal tumor irradiation. Acute effects were unacceptable, with 11 of the 18 dogs developing severe mucositis, desquamation, edema, swelling, and pruritus. The extensive nature of the acute reactions compromised assessment of the effect of the increased radiation dose on the tumor. Although there is justification for assessing more aggressive radiation protocols in canine nasal tumor patients, total doses approximating 60 Gy can not be given as described because of the inability of acutely responding normal tissues to compensate.