L. Sicardrosenbaum et al., EFFECTS OF CONTINUOUS THERAPEUTIC ULTRASOUND ON GROWTH AND METASTASISOF SUBCUTANEOUS MURINE TUMORS, Physical therapy, 75(1), 1995, pp. 3-11
Background and Purpose. The use of therapeutic ultrasound (US) in the
presence of malignant neoplasms has been contraindicated in physical t
herapy practice despite a lack of convincing scientific evidence. Some
studies have shown that high levels of US, which increase tissue temp
eratures greater than 42-degrees-C, can kill tumors. We sought to dete
rmine whether the application of continuous therapeutic US would alter
the growth or metastasis of methylcholanthrene-induced solid tumors i
n mice. Subjects. Seventy-one female C57BL/6 mice, age 6 to 8 weeks, r
eceived subcutaneous injections of 5 x 10(5) tumor cells. Methods. Whe
n tumors grew to 0.5 cm in diameter, the mice were randomly assigned t
o either a control group (n=34) or an experimental group (n=37). The e
xperimental group received 10 treatments over a 2-week period of 3-MHz
continuous US at 1.0 W/cm2 for 5 minutes, using a 0.5-cm2 sound head
directly over the tumor. The control group received the same handling
except for the US treatment. Tumor dimensions were measured on days 1
(baseline), 7 (midtreatment), and 14 (preexcision and postexcision). T
umors were weighted after excision, and the mice were evaluated by nec
ropsy and histopathology of regional lymph nodes. Results. All tumors
grew larger over time, but final tumor volume and weight were larger i
n the experimental group (789 mm3 and 0.932 g) than in the control gro
up (395 mm3 and 0.506 g). No significant difference existed in the num
ber of metastatic lymph nodes between groups. Conclusion and Discussio
n. Continuous therapeutic US increased the volume and weight of subcut
aneous murine tumors in mice. We urge caution in the use of continuous
therapeutic US in the areas of tumors or suspected tumors.