10 General Aspects of Head and Neck Brachytherapy

General Aspects of Head and Neck Brachytherapy

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THE GEC ESTROHANDBOOKOF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 30/01/2019

Moreover, in particular situations, such as postoperative brachytherapy if the surgical margins are inadequate, the total dose usually ranges between 45Gy to 60Gy when brachytherapy alone is used or between 20Gy and 30Gy when PDR brachytherapy is combined with external irradiation. 9.3. HDR HDR is defined as a dose rate equal to or greater than 12Gy/h(= 200 cGy/min). HDR brachytherapy is delivered in fractions that are usually separated at least 6 hours in order to allow full sublethal damage repair. In practical terms, most patients are treated on a twice-a-day schedule to comply with department logistics. . Dose per fraction, -usually prescribed at the CTVD 90 - ranges from 2.5Gy to 6Gy, with 2 fractions per day for a total dose ranging from 32Gy to 48Gy when brachytherapy is used alone, and from 10Gy to 21Gy when brachytherapy is combined with external irradiation. The smaller the dose per fraction, the better the normal tissue tolerance. A meta-analysis comparing the results with LDR/PDR and HDR brachytherapy was published in 2013 in more than 600 patients with oral cavity cancers stages I-III. The conclusion was that the two treatment modalities were equivalent in terms of local control, survival and complications [29]. PDR and HDR brachytherapy absorbed doses to the CTV and OARs should be converted into EQD2 values to allow addition with conventionally-delivered external irradiation as well as to allow meaningful comparison with other treatment regimens (Sections 8.5 and 8.7). 10. BRACHYTHERAPY IN PREVIOUSLY IRRADIATED CASES AND OTHER SPECIAL SCENARIOS 10.1. Types of previously irradiated cases The majority of previously irradiated head and neck cancers is comprised by patients who relapse at locoregional sites after primary or adjuvant radiotherapy, usually during the first 2 or 3 years of follow-up. An additional 5 to 10% of previously irradiated cases are patients who received irradiation in the head and neck area in the past and have developed second primary cancers within the irradiated volume after a variable length of follow-up. Clinical management is limited in both scenarios by the prior delivery of irradiation as well as other treatments such as surgical resection in many cases. However, the former group usually presents an unfavorable outcome. The use of brachytherapy after prior irradiation should be done with caution in all cases and should follow the general guidelines used for reirradiation with external beams [30]. In general, a limited dose to a limited volume seems a reasonable approach. In that regards, brachytherapy seems to be especially suited for the management of previously irradiated lesions due to its unparalleled dose distribution. The time elapsed between the primary and the current radiation course should also be taken into 10.2. Special considerations on Dose-volume parameters

Fig 13. Cumulative Hazard of grade 3 or greater complications after perioperative HN BT as a function of prior irradiation and TV150 values ≥ 13 cc. Solid line (lowermost) indicates absence of risk factors; middle dotted line indicates presence of 1 factor; Higher dotted line indicates presence of both factors. Taken from Martínez-Monge et al [23].

consideration, because in certain tissues, some degree of recovery may be expected with time [31], and therefore, more dose-volume flexibility can be applied in cases appearing many years after the primary radiation course. In a study of 103 patients with HNC treated with perioperative HDR brachytherapy combined or not with EBRT or chemoradiation conducted at the University of Navarre [23] prior irradiation correlated with grade ≥3 and grade ≥4 complications (p = 0.032 and p = 0.006, respectively). TV 150 values of 13 cm 3 or more also correlated with grade ≥3 and grade ≥4 complications (p = 0.032 and p = 0.032, respectively). Patients with prior irradiation and TV 150 ≥ 13 ccmhad a much higher cumulative risk compared with the patients with one or none of the two risk factors (Figure 13). 11.1. Nursing Control Daily patient follow-up is essential during brachytherapy. The implanted areamust be systematically checked for signs of infection, bleeding and correct localization of the tubes. Any bleeding should be checked and registered as it may have an impact not only on the patient status, but also on the catheter removal modalities. In case of perioperative brachytherapy, special care has to be taken of the combined surgery. If a flap reconstruction was performed, wound healing complications have to be systematically searched, such as flap dehiscence which may be present in up to 32% of the cases [32]. 11.2. Implant Check and Treatment Delivery The implant must be systematically checked for catheter kinking or displacement. Special care has to be taken of the catheters to avoid kinking. Nowadays, catheters are usually placed in a straight 11. PATIENT CARE DURING BRACHYTHERAPY