Influence of concurrent anastrozole on acute and late side effects of whole breast radiotherapy.

OBJECTIVES: To retrospectively compare radiation toxicity in patients treated with concurrent anastrozole and whole breast irradiation versus women treated sequentially with whole breast irradiation followed by hormonal suppression. METHODS: The records of 249 consecutive estrogen or progesterone receptor positive breast cancer patients treated with breast-conserving surgery and postoperative whole breast irradiation were reviewed. Of total, 57 patients (the concurrent anastrozole group) received concurrent anastrozole prior to and during radiotherapy. In 126 patients (the sequential group), adjuvant hormone suppression therapy (anastrozole, other aromatase inhibitors, or tamoxifen) was administered after the completion of breast irradiation. In 66, women either concurrent tamoxifen was given with radiation or the sequence of hormonal therapy was not known. These women were excluded from the analysis. RESULTS: The frequency of acute grade 2 radiation dermatitis (24.6% in the concurrent anastrozole group vs. 20.6% in the sequential group; P = 0.55), grade 3 radiation dermatitis (8.8% vs. 7.1%; P = 0.77) and treatment interruptions due to skin reactions (14.0% vs. 11.2%; P = 0.69) did not differ between groups. The rates of clinically detectable breast fibrosis were not different (24.2% vs. 24.7%; P = 0.97). With a median follow-up of 28 months and 30.8 months, respectively, 1 local failure occurred in the concurrent anastrozole group and 5 in the sequential group. CONCLUSIONS: Anastrozole, administered concurrently with whole breast irradiation, did not increase acute or late morbidity when compared with sequential administration of radiation and hormonal suppression therapy.

Hypothermia-enhanced human tumor cell radiosensitivity.

Ablation of neoplastic disease by freezing has found increasing utility as a potential therapeutic modality. To assess the effect of cooling temperatures on cellular radiation response, an established human cervical carcinoma cell line (HTB35) was subjected to holding temperatures of 0, 5, or 15 degrees C for up to 24 h before irradiation. Survival was measured by in vitro clonogenic assay of colonies containing at least 50 cells. Cooling for up to 12 h did not significantly decrease survival, but after 24 h survival fell to 75% of control cultures grown at 37 degrees C. X-irradiation immediately after cooling for 24 h resulted in 1.6-fold enhanced radiosensitivity. However, the radiosensitizing effect decayed rapidly if the cooled cells were returned to normal growth temperature for 6 h or longer before irradiation and subculture. Both temperature and cooling duration influenced the radiation response. With 0, 5, or 15 degrees C, radiosensitivity increased after 3, 6, or 12 h, respectively, and progressively rose with up to 24 h of cooling. By flow cytometric analysis, no statistically significant difference was observed in the S-phase fraction between control cells and those cooled to 0 degree C for 24 h. These data demonstrate cooling-enhanced in vitro radiation sensitivity which is dependent upon cooling temperature, duration, and rewarming interval before irradiation. While cell cycle redistribution does not appear to be a factor in the increased radiosensitivity, differences in the radiation survival curves between cooled versus normothermic cells suggest that diminished capacity for sublethal damage repair may be a significant influence on the changes which were observed.

Radiation survival of two human cervical carcinoma cell lines after multifraction irradiation.

PURPOSE: Multifraction irradiation may contribute to radiation therapy treatment failure if selection of radiation resistant subpopulations occurs. We sought to determine whether surviving cells following daily fraction irradiation of two human cervical squamous cell carcinoma lines would express different radiation survival characteristics compared to the unirradiated parent. METHODS AND MATERIALS: A late-passage line (HTB35) and an early-passage line (RECA) received daily 2 Gy x-irradiation. Two new stable HTB35 cell lines were established after 40 and 60 Gy (HTB35-40 and HTB35-60). A single line was established from RECA after 30 Gy (RECA-30). High dose rate (74 cGy/min) acute radiation survival curves were prepared from the three new lines and the unirradiated parents. Potentially lethal damage repair (PLDR) and sublethal damage repair (SLDR) responses were detailed for HTB35, HTB35-40 and HTB35-60. Low dose rate (1.27 cGy/min) survival was measured for HTB35 and HTB35-60. Clones were derived from HTB35 and from HTB35-60 and the surviving fraction at 2 Gy (SF2) values were determined. RESULTS: The two parent lines (HTB35 and RECA) differed in acute radiation survival. The surviving lines following multifraction irradiation (HTB35-40, HTB35-60, and RECA-30) showed no change in acute radiation response compared to the appropriate parent. HTB35-40 and HTB35-60 were repair proficient, demonstrating similar PLDR and SLDR recovery ratios as the parent. Likewise, acute, low dose rate survival of HTB35 and HTB35-60 was similar. Nine clones derived from HTB35 lacked a consistent difference in SF2 compared to the original culture. A single clone of seven derived from HTB35-60 was consistently radiation resistant (SF2 = 0.81 +/- 0.06) compared to the original culture (SF2 = 0.50 +/- 0.09). CONCLUSION: No evidence was obtained that cell lines generated following multiple daily fractions of x-irradiation in vitro possessed acute radiation survival or repair characteristics that were different from the unirradiated parent.

Calorimetric evaluation of antennas used for microwave interstitial hyperthermia.

Several quasi-adiabatic calorimeters have been constructed for determining the heating efficiency of microwave antennas. The absorber is 0.9% saline which is stirred continuously, making equilibration times short (several seconds). Depth of insertion data have been obtained for standard BSD and CTC antennas at 915 MHz. Efficiency varies only slightly with insertion depth in the range 7-16 cm and can be as high as 65%. At shallower depths efficiency drops off, while reflected power and leakage fields increase. Data obtained in site visits conducted by the Hyperthermia Physics Center show that antenna efficiency of the BSD and CTC models can vary by as much as 35% within sets of functional 'identical' antennas.

Relationships between cellular superoxide dismutase and susceptibility to chemically induced cancer in the rat mammary gland.

Increasing evidence suggests a role for reactive free radical oxygen species in the multi-stage events of chemical carcinogenesis. We hypothesized that variations in the level of superoxide dismutase (SOD), a major endogenous antioxidant enzyme, may account in part for variations in susceptibility to cancer induced by polycyclic aromatic hydrocarbons (PAH). The SOD activity of mammary epithelial cells from rats with varying susceptibility to dimethylbenz[a]anthracene (DMBA)-induced breast cancer was assayed. Ageing, pregnancy and previous multiple pregnancies reduce susceptibility of Sprague--Dawley female rats to DMBA. These decreases in susceptibility were correlated with increased levels of SOD activity. Only minor differences in SOD activity was observed in mammary epithelium of genetic strains of rats with differences in susceptibility to DMBA. These data suggest that, in models where physiological differences may account for variations in effectiveness of PAH to induce mammary cancer, SOD activity is inversely correlated with breast cancer susceptibility and support the hypothesis that cancer susceptibility may be partially mediated through reactive free radical oxygen intermediates.

Temporal response of murine bone marrow to local hyperthermia.

Hemopoietic insufficiency resulting from single or multiple agents used in cancer therapy often becomes a dose limiting toxicity. Since hyperthermia is finding increased clinical application with whole body or extended field treatments for a variety of neoplastic diseases, we wished to examine its potential effects on normal bone marrow. One hind leg of anesthetized mice received up to one hour water bath heating to 41-44 degrees C. With temperatures of 42 degrees C or greater, there was a dose and heating time dependent initial depletion of both CFU-S and CFU-GM that was not appreciably affected by migration of stem cells to or from the heated field. CFU-S and CFU-GM returned to normal values by 2 to 3 weeks after 1 hour heating to 42 degrees C. However, at 43 degrees or 44 degrees C for 1 hour, CFU-GM only transiently returned to normal, falling to 55% and 33% of control respectively by 3 months. Total nucleated cell counts reflected a similar dose and time dependent depletion and repopulation. Finally, bone marrow differential counts from heated marrow suggested that equivalent repopulation along each differentiation pathway occurred during recovery after thermal injury. These data indicate that temperatures greater than 42 degrees C for one hour caused a long term delay in hemopoietic repopulation, which may contribute to a significant toxicity when hyperthermia is used in combination with chemotherapeutic drugs or local irradiation incorporating the same treatment field.

Characterization of marrow stromal (fibroblastoid) cells and their association with erythropoiesis.

Our previous studies suggested that a defect in the hemopoietic microenvironment of bone marrow occurred in the anemia of chronic inflammatory disease. We examined the in vivo hemopoietic and marrow stromal cell (MSC) response of shielded marrow to 5000 rad leg-irradiation (5000 rad LI), the in vitro growth of BFUE, CFUE, and CFUC in co-culture with MSC, and the in vitro characteristics of MSC. One month after 5000 rad LI, erythroblasts and MSC fell to 18% and 26% respectively. BFUE and CFUE in shielded marrow increased 1.5 to 2 times. Total CFUS and CFUC were normal. In co-culture, small numbers of MSC enhanced BFUE and CFUE, but suppressed CFUC. MSC in colonies were polygonal cells with a plating efficiency of 10 per 10(6) nucleated marrow cells and 1 per 10(6) spleen or nucleated blood cells. MSC were not phagocytic and did not stain with nonspecific esterase. We conclude that in mice with an inflammatory response to 5000 rad LI: 1) Erythroblasts and MSC decreased while erythroid progenitors (BFUE and CFUE) increased in the shielded marrow, 2) MSC stimulated BFUE and CFUE in co-culture, 3) MSC in colonies were adherent, large polygonal cells that may enhance erythroid maturation in the bone marrow.