The Use of a High-frequency Ultrasonic Knife in Breast Cancer Surgery
The Use of a High-frequency Ultrasonic Knife in Breast Cancer Surgery
Background: Lymphatic stasis and seroma formation are common complications of axillary
 lymphadenectomy in breast cancer surgery. The investigators aim is to test the hypothesis
 that the use of an ultrasonic knife for axillary dissection reduces the total amount and
 duration of persistent drainage and length of hospital stay. Method: The investigators have
 conducted a randomized trial on 94 patients (1 male, 93 females, mean age 64.7 years) who
 presented to the investigators unit with operable breast carcinoma. Patients in group A (38
 cases) were operated on using exclusively the ultrasonic knife. Patients in group B (56
 cases) were operated on using the conventional diathermy knife.
The ultrasonic knife we have used in our study exploits the electrical impulses produced by a
 high-frequency ultrasound generator, transferred to a hand piece and converted into a
 mechanical movement at a frequency of 55.5 kHz (11,12) (Ultracision®, Ethicon Endo Surgery ).
 We have chosen this instrument because the relatively low temperatures generated in the
 process, ranging from 50 to 100 °C, result in a coagulative necrosis which allows both
 cutting and effective sealing of blood and lymphatic vessels, therefore preventing lymphatic
 leaks more effectively compared with conventional diathermy. The latter produces temperature
 up to 400 °C resulting in char formation and deleterious thermal effects to a distance of up
 to 1cm from the blade and extensive formation of necrotic tissue.

 We have estimated Using the data of a previous unpublished pilot study, the sample size
 required for our trial using the data of a previous unpublished pilot study, indicating that
 to detect a significant difference in length of stay (delta = 4of four days, with a mean
 standard deviationsdigma of = 4.5 days, between the two groups with a level of significance
 of alpha = 5% and a power of1 - beta = 90%), we needed to enroll was estimated in 28 patients
 in each group arm. As a precaution we decided to increase the sample size by 25% to 35
 patients per group arm, in case we needed to use non-parametric tests in subsequent
 statistical analysis. A total of 94 patients with operable breast carcinoma were recruited
 between January 2000 and December 2004: 1 male and 93 females (min 34, q1 58, median 65, mean
 64.7, q3 73, max 95). All patients underwent total mastectomy or quadrantectomy and 1st or
 2nd level axillary lymphadenectomy. Patients were randomly allocated to two treatment groups:
 patients allocated to Group A were operated on using exclusively the ultrasonic knife
 (Ultracision®, Ethicon Endo Surgery) for both the mastectomy or quadrantectomy and axillary
 dissection (38 cases, mean age of 64.6 years, min 34, q1 58, median 66, q3 70, max 95);
 patients allocated to Group B (control group) were operated on using a conventional
 diarthermy knife was (56 cases, mean age of 65.0 years,min 37, q1 59, median 65, q3 74, max
 89). In all cases the type of a redon n°14 suction drain was left in the axillary cavity and
 removed as soon as the amount of fluid dropped to 35 ml/24h or less. The patient was
 discharged home the same day the drain was removed.

 During the postoperative period the following data were collected: the total amount of fluid
 drained, the number of days the drain was leftof drainage, the length of post-operative stay,
 and early and late complications. Early complications were specifically recorded: wound
 seromas and hematomas, wound infections, necrosis of wound margins and period of time (in
 days) the seroma needed to be needle-aspirated following removal of the drain. Late
 complications recorded were lymphedema, strength and sensation deficits and chronic arm pain.
 A cost analysis was also done considering materials employed and length of hospital stay.
 Statistical analysis was done using open source "R" software, version 2.5.1 (18). The
 Shapiro-Wilk test was used to verify the normal distribution of data; heteroscedastic,
 normally distributed data were analysed using the F-test of variance; Student's t test was
 used for homoscedastic data. For non normally distributed data the non-parametric
 Wilcoxon-Mann-Whitney test was used. Survival analysis was analysed using Cox's regression
 model, in the hypothesis of proportional risk.
Inclusion Criteria:

 -  Operable breast cancer

 Exclusion Criteria:

 -  Inoperable breast cancer

 -  BMI > 25

 -  Neoadiuvant radioterapy

 -  Carcinomastitis

 -  Previous phlebitis of omolateral arm

 -  Collagen disease