Postoperative radiotherapy in breast cancer--long-term results from the Oslo study

Radiotherapy following mastectomy: indication and contraindication of chest wall irradiation

PURPOSE

To determine in which cases radiotherapy of the chest wall following mastectomy is indicated, based on the local recurrent rate in patients with locally advanced breast cancer.

METHODS AND MATERIALS

From 1984 until 1994, 105 patients who had four or more histopathologically confirmed axillary nodes metastases, or T3-4Nany, were subjected to mastectomy and were administered radiotherapy postoperatively using the hockey-stick field, which included the ipsilateral supraclavicular fossa and internal mammary nodes, except the chest wall. Median age was 51 years old (range, 23 to 82 years old). Eighty-five patients underwent radical mastectomy, 18 modified radical mastectomy, and 2 extended radical mastectomy. Fraction size was 2 Gy/day, the weekly fraction size was 10 Gy and the total dose ranged from 44 Gy to 54 Gy (median 50 Gy). Seventy-four patients were administered adjuvant chemotherapy, and 61 patients were administered hormone therapy.

RESULTS

The 5-year disease-free survival rates of the whole study population were 66%. The 5-year chest wall recurrence rates were 10%. The 5-year chest wall recurrence rates of the patients who had no vascular invasion (n = 19) and the patients who had definite vascular invasion (n = 38) were 0% and 24%, respectively (p = 0.036). All the patients who presented chest wall recurrence had four or more axillary nodes metastases. Nine of the 10 patients who presented chest wall recurrence had definite vascular invasion, while there was no information about vascular invasion for the remaining patient. Factors such as age, pathological subtypes, tumor location, estrogen receptors, extent of resection, chemotherapy, and hormone therapy did not influence the development of chest wall recurrence.

CONCLUSION

Among patients with breast cancer who have four or more positive axillary nodes or T3-4Nany, those who have no vascular invasion or less than 4 axillary nodes metastases do not need to be subjected to chest wall irradiation after radical mastectomy.

Postmastectomy radiotherapy: randomized trials

Postmastectomy radiotherapy decreases threefold the risk of locoregional recurrences according to the results of many randomized trials and overviews. This risk is mainly related to the number of involved axillary nodes (ie, about 25%, 35%, and 55% at 10 years when 1 to 3, 4 to 9, and 10 or more nodes are involved). In contrast, at 10 years, fewer than 15% of patients with negative axillary nodes relapse locally. The effect of postmastectomy radiotherapy on distant metastases and overall survival is a controversial issue. On the one hand, results are compatible with the existence of a mechanism of secondary dissemination generated from locoregional tumor nests. The beneficial effect of radiotherapy may be observed in the absence or presence of adjuvant systemic treatment. On the other hand, a deleterious late toxic, mainly cardiac, effect of radiation has also been shown. This point emphasizes the importance of radiation technique and quality to obtain a positive balance in terms of overall survival.

Postmastectomy radiotherapy: toxicities and techniques to reduce them

The role of locoregional radiation therapy after mastectomy is controversial. It reduces the risk of tumor relapse, improves breast cancer-specific survival and possibly overall survival, but has potential morbidity. This article reviews the technical aspects of postmastectomy radiation therapy and its associations with treatment-related morbidity. We consider common problems that arise in the technical setup of radiation fields. Adverse effects of postmastectomy radiation therapy may be reduced or prevented by careful radiation treatment planning.

Postmastectomy radiation in patients with one to three positive axillary nodes receiving adjuvant chemotherapy: An unresolved issue

The rationale for postmastectomy radiation is based on the prevention of locoregional recurrence in the chest wall, regional lymphatics, or both. The randomized trials of postmastectomy radiation in patients with one to three positive nodes receiving adjuvant chemotherapy have shown a proportional reduction in locoregional recurrence rates of two thirds. The absolute benefit, however, varies with the magnitude of the risk in patients who do not receive radiation. The survival benefit from radiation is best explained by the prevention of an isolated locoregional recurrence, which could serve as a source of fatal distant metastases and parallels the difference in the total incidence of distant metastases. The current dilemma is to identify patients with one to three positive nodes who have had an adequate axillary dissection and remain at substantial risk for a locoregional recurrence despite adjuvant chemotherapy. The routine use of postmastectomy radiation in all axillary node-positive patients requires further evaluation.

Assessing the cost-effectiveness of postmastectomy radiation therapy

PURPOSE

To assess the cost-effectiveness of postmastectomy local-regional radiation therapy (RT) for patients with breast cancer with regard to local-regional relapse (LRR) and quality-adjusted life years (QALY).

METHODS AND MATERIALS

Data from the literature are used to estimate the risk of LRR, and the impact of RT on the risk of LRR and survival. The risk of LRR is related linearly to the number of positive axillary nodes 1% rate of LRR = 10 + (4 x number of positive nodes)]. RT reduces the risk of LRR by 67%. LRRs are treated with excision or biopsy followed by RT; half being controlled locally and half receiving additional salvage surgery and chemotherapy. Absolute improvements in 10-year overall survival due to RT are assumed to vary between 1 and 12%; and accrue linearly during the initial 10-year follow-up period. Professional and technical charges are used as a surrogate for costs. Money spent and benefits recognized in future years are discounted to 1997 values using a 3% annual rate. Quality factors are used to adjust for treatment, disease, and toxicity status.

RESULTS

The cost per LRR prevented with the addition of routine postmastectomy RT is highly dependent upon the number of positive axillary nodes and ranges from $100,000-$200,000 for patients with 0-2 nodes, and $25,000-$75,000 for > or = 4 nodes. The cost per QALY gained at 10 years is $10,000-$110,000 for survival benefits > or = 3%.

CONCLUSIONS

The cost per LRR prevented decreases with increasing numbers of positive axillary nodes. There is not a sharp cutoff at the < or = 3 vs. > or = 4 lymph node number, suggesting that using this cutoff for recommending or not recommending RT following mastectomy is not economically logical. The cost per QALY of $10,000-$100,000 compares favorably to that of other accepted medical procedures. Modest changes in the quantitative assumptions do not qualitatively alter the results. Concerns regarding costs should not generally preclude the use of postmastectomy RT.

Evaluation of predictive factors for local tumour control after electron-beam-rotation irradiation of the chest wall in locally advanced breast cancer

BACKGROUND AND PURPOSE

Different radiotherapy techniques are being used for chest wall irradiation after mastectomy. We review our results with the electron-beam-rotation technique in a series of 130 high risk breast cancer patients. The main end point of the study was local tumour control; secondary end points were disease free survival, and overall survival, as well as acute and late side effects.

MATERIAL AND METHODS

From January 1990 to June 1995, 89 patients underwent electron-beam-rotation irradiation of the chest wall after primary mastectomy and axillary lymph node dissection (group I) and 41 patients after excision of local recurrent breast cancer (group II) with 4 x 2.5 Gy/week to 50 Gy total dose (4-12 MeV electrons depending on the thickness of the chest wall). In addition, irradiation of local-regional lymph nodes and/or a local boost of 10 Gy were applied dependent on the resection and node status.

RESULTS

After a median follow up of 29 months (65% stadium III/IV) the 3 year local tumour control, disease free survival, and overall survival were 73%, 47%, and 75%, respectively. Local control in group I was 78% versus 60% in group II. Significant predictors for local tumour control, disease free survival, and overall survival were resection status (R0 versus R1/2) and estrogen receptor status (positive versus negative). In group I, tumour grading (GI-IIa versus GIIb-III) and estrogen receptor status were found to be additional significant prognostic factors for complete resected tumours. Five patients developed symptomatic pneumonitis (< 4%) and one patient developed a chronic fistula at the resection. A significant correlation between the degree of acute skin reaction and persistent pigmentation was observed.

CONCLUSION

In high risk breast cancer patients postoperative irradiation with the electron-beam-rotation technique of the chest wall is an effective therapy resulting in 78% local tumour control at 3 years for locally advanced breast cancer and 60% for recurrent disease. The rate of acute and late toxicity is low. The degree of acute skin reaction correlates with the degree of persistent pigmentation.

Loco-regional recurrences after mastectomy in breast cancer: prognostic factors and implications for postoperative irradiation

PURPOSE

Potential risk factors including DNA flow cytometric-derived parameters predicting loco-regional recurrence (LRR) in early breast cancer were investigated.

MATERIALS AND METHODS

This study included 608 patients treated by modified radical mastectomy between 1982 and 1987. Recommendations regarding local treatment as well as adjuvant systemic therapy did not change during this period. Patients treated by adjuvant chemotherapy were randomized to receive additional medroxyprogesterone acetate (MPA) treatment. Only 59 (10%) patients received postoperative irradiation (XRT) to the chest wall and/or axillary lymph nodes; another 121 (20%) patients received XRT to the internal mammary nodes because of centromedially located tumours.

RESULTS

Patients were followed for a median period of 7.5 years. The event-free survival at 10 years was 50%. The cumulative incidence rate of LRR at 10 years was 18% (n = 93), either with (n = 30) or without (n = 63) concurrent distant metastases. The chest wall, regional lymph nodes or both were involved in 41 (44%), 38 (41%) and 12 (13%) patients, respectively. Multivariate analysis according to the Cox model revealed two factors associated with LRR, i.e. pT (P < 0.05) and nodal status (P < 0.05). In node-positive patients extracapsular tumour extension (ECE) and pT were independent risk factors. DNA ploidy and S-phase fraction did not yield additional information. Based on pT, nodal status and extracapsular extension of tumour growth a high risk (> 10%) and low risk (< 10%) group for LRR could be identified.

CONCLUSIONS

Results indicate that T-stage and nodal status, combined with ECE, may help to identify patients at risk for loco-regional recurrence, whereas DNA flow cytometry does not.

No serious late cardiac effects after adjuvant radiotherapy following mastectomy in premenopausal women with early breast cancer

PURPOSE

To assess cardiac mortality, coronary artery disease, myocardial dysfunction, and valvular heart disease in women younger than 65 years of age, at least 10 years after adjuvant radiotherapy following mastectomy in early breast cancer.

METHODS AND MATERIALS

Ninety women (45-64 years old) with Stage II breast cancer without relapse, included in the South Sweden Breast Cancer Trial (premenopausal arm), with or without adjuvant postoperative radiotherapy +/- cyclophosphamide were examined with myocardial scintigraphy and echocardiography/Doppler, 10-17 years after radiotherapy. Thirty-four patients had been irradiated for left-sided tumors, 33 for right-sided tumors, and 23 patients had not been treated with radiotherapy. The radiotherapy (conventional roentgen, electron beams, and high-energy photon beams combined, in each patient) included the chest wall and the regional lymph nodes, with a specified target dose of 38-48 Gy, administered in daily fractions of 1.9-2.4 Gy, 5 days/week.

RESULTS

No cardiac deaths were found among the original 275 patients randomized to adjuvant therapy. In the 90 patients examined, abnormal findings were recorded for ECG (14 patients), exercise test (5 patients), myocardial scintigraphy (6 patients), thickening of valve cusps (14 patients), and mild valvular regurgitation (20 patients). All patients had normal systolic function. Diastolic dysfunction was observed in 6 patients (abnormal relaxation in 4 patients and restrictive filling abnormality in 2 patients). Although no significant differences were found between the 3 study groups, there was a tendency to more abnormal findings after radiotherapy.

CONCLUSION

Women younger than 50 years of age at the time of adjuvant radiotherapy following mastectomy in early breast cancer, had no serious cardiac sequelae 13 years (median) later, despite partly old-fashioned radiation techniques.

Mortality from myocardial infarction following postlumpectomy radiotherapy for breast cancer: a population-based study in Ontario, Canada

PURPOSE

To compare the risk of mortality from myocardial infarction (MI) after left-sided postlumpectomy radiotherapy (RT) to the risk after right-sided postlumpectomy RT.

METHODS

We conducted a population-based cohort study of cases of invasive female breast cancer in Ontario, diagnosed between January 1, 1982 and December 31, 1987 (n = 25,570). Records of the Ontario Cancer Registry (OCR) were linked to hospital procedure and discharge abstracts and to RT records from Ontario cancer centers. A case was labelled as lumpectomy if this was the maximum breast surgery within 4 months of diagnosis. Postlumpectomy RT occurred up to 1 year postdiagnosis. Laterality was assigned from the laterality descriptor of the RT records. A case was labelled as having had a fatal MI if ICD code 410 (myocardial infarction) was recorded as the cause of death in the OCR. We used logistic regression to compare the likelihood of utilization of: 1. Dose per fraction > 2.00 Gy; 2. cobalt vs. linac; and 3. boost RT. We used life table analysis and the log rank test comparing the time to fatal MI from diagnosis of breast cancer between women who received left-sided postlumpectomy RT and women who received right-sided. We used Cox proportional hazards models to study the relative risk for left-sided cases overall, and stratified by age, RT characteristics, and among conditional survival cohorts.

RESULTS

Postlumpectomy RT was received by 1,555 left-sided and 1,451 right-sided cases. With follow-up to December 31, 1995, 2% of women with left-sided RT had a fatal MI compared to 1% of women with right-sided RT. Comparison of the time to failure between women who had left-sided RT and women who had right-sided RT showed the left-sided RT group to be associated with a higher risk of fatal MI (p = 0.02). Adjusting for age at diagnosis, the relative risk for fatal MI with left-sided postlumpectomy RT was 2.10 (1.11, 3.95).

CONCLUSION

Among women who received postlumpectomy RT for breast cancer in Ontario between 1982-1987, left-sided postlumpectomy RT was associated with a higher risk of fatal MI compared to right-sided.

The link between local recurrence and distant metastases in human breast cancer

PURPOSE

To distinguish between two possible explanations for the increased incidence of distant metastases observed in patients with locoregional recurrences (LR). Either LR is the signature of tumor aggressiveness, and avoiding recurrences (i.e., by radiotherapy) is of little value. The alternative is that LR is a nidus for metastatic dissemination.

METHODS AND MATERIALS

Four thousand patients consecutively treated in the same institution from 1954 to 1975 were studied. None of them had received adjuvant chemotherapy. Tumor characteristics, local recurrence, and distant metastases had been prospectively registered. Duration of metastatic growth and probability of metastatic dissemination were estimated in the subsets of patients.

RESULTS

The proportion of metastasis-free patients was reduced by about 80% in all subsets of patients with LR. In patients without LR, the monthly rate of distant metastases incidence decreases continuously with time after initial treatment. Conversely, in patients with local recurrence, this rate increases during the first year at initial treatment and the metastases in excess appear slightly later than in patients without local recurrence. Using a mathematical model, it can be shown that, in patients with local recurrence, nearly all of the metastases in excess had been initiated after initial treatment. The data also suggest that each year a small proportion of grade 1 residual tumors progresses toward a more malignant histologic type.

CONCLUSIONS

Our results are not consistent with the hypothesis that a greater tumor aggressiveness in patients with LR could explain the excess of metastases. This conclusion is supported by the analysis of the delays between metastases' emergence, and death, which shows that tumors with or without LR have similar biological characteristics.

Coronary artery operation in patients after breast cancer therapy

OBJECTIVE

The purpose of this investigation was to retrospectively study the outcome of patients undergoing coronary artery operation who were previously treated for breast cancer.

METHODS

Between July 1992 and December 1996, 28 patients with a history of breast cancer underwent coronary artery bypass graft operation and were randomly matched against a noncancer group of similar size (n = 36) to allow for comparison of their preoperative characteristics, operative course, and postoperative outcome.

RESULTS

The incidence of sternal wound infection was significantly higher in the cancer group than in the control group (25% versus 6%; p = 0.027). Postoperative noncardiac chest pain occurred more frequently in the cancer group than in the control group (52% versus 31%; not significant). In the study group, radiotherapy and recent myocardial infarction were the only two independent factors associated with sternal wound complications. Patients with a less than 17-year interval between the breast cancer therapy and the coronary artery operation had a higher incidence of sternal wound infection (46%) as opposed to patients with a longer time interval (7%; p = 0.028; odds ratio = 12). Sternal wound complications were more frequent in patients with a history of right-sided breast cancer (50%) compared with left-sided lesions (12.5%; p = 0.068; odds ratio = 7).

CONCLUSIONS

Coronary artery operation in patients after breast cancer therapy may be associated with an increased sternal wound infection rate. To decrease this risk of infection, an approach through a right thoracotomy, minimally invasive techniques, the use of skeletonized internal mammary artery, and broad spectrum antibiotic therapy may be considered.

[Influence of locoregional irradiation on local control and survival in breast cancer]

Locoregional control is a crucial step in the achievement of breast cancer cure. In ductal carcinoma in situ, breast irradiation significantly reduces the rates of local recurrence whatever the histological subtypes, as demonstrated by the NSABP-B17 trial (25.8% of local recurrences without radiotherapy vs. 11.4% with radiotherapy). In infiltrating breast carcinomas, complementary breast irradiation has been shown to significantly improve the local control and slightly the overall survival in five randomized trials. Following mastectomy, locoregional irradiation clearly reduces the chest wall and nodal relapse rates, especially in case of lesions more than 5 cm or with nodal involvement and/or large lymphatic or vascular emboli. Two recent randomized trials confirmed the benefit of well-adapted locoregional irradiation in all subgroups, especially in patients with one to three axillary involved nodes. In the Danish trial (including premenopausal high-risk women), radiotherapy reduced locoregional relapses from 32 to 9% (p < 0.001) and increased the 10-year survival rate from 45 to 54% (p < 0.001). In the Canadian trial, locoregional relapse rate decreased from 25 to 13% and the 10-year survival rate increased from 56 to 65%. The meta-analysis published in 1995 by the EBCTCG showed only a modest benefit due to locoregional irradiation in breast cancer. However, when small or old trials were excluded due to imperfect methodology or inadequate irradiation techniques, the benefit of modern radiotherapy became much more evident in a population of 7,840 patients. Locoregional irradiation appears to be able to reduce the risk of metastatic evolution occurring after local or nodal relapse and must be integrated in a multidisciplinary strategy. Treatment toxicity (especially toxicity due to irradiation of internal mammary nodes) is of special concern, as anthracycline-based chemotherapy is prescribed more often. The use of a direct field, with at least 60% of the dose delivered by electrons alternating with photons is recommended to protect the heart and lungs.

Thallium-201 perfusion scintigraphy in the evaluation of late myocardial damage in left-side breast cancer treated with adjuvant radiotherapy

PURPOSE

To evaluate late myocardial damage after adjuvant radiotherapy using a mixed-beam (photons plus electrons) technique to treat the internal mammary lymph nodes in left-side breast cancer.

METHODS AND MATERIALS

A bicycle ergometer stress test coupled with thallium-201 perfusion scintigraphy and analysis by single-photon computed tomography (CT) was performed on 19 patients treated with left-side breast/chest wall and internal mammary radiation for breast cancer between 1987 and 1993. To be sure that we would evaluate late toxicity caused by the irradiation, patients had to fulfill the following eligibility criteria: left-side breast cancer, treatment between 1987 and 1993 and no recurrence during follow-up, age < or = 75 years, no known risk for coronary artery disease, no previous chemotherapy, internal mammary field treated with an association of photons and electrons, and CT scan-based treatment planning.

RESULTS

Median age at scintigraphy was 59 years. Two patients did not reach optimal exercise level and were not evaluable. Among the 17 evaluable patients representing 91.6 patient years of follow-up, there were no perfusion defects by visual or quantitative analysis.

CONCLUSION

The mixed-beam technique seemed to spare the heart from harmful irradiation and to protect the myocardium. Results need to be confirmed on the long-term use of this technique.

Diagnostic thoracic-computed tomography in radiotherapy for loco-regional recurrent breast carcinoma

PURPOSE

This study was initiated to evaluate whether pretreatment diagnostic thoracic CT scan was useful for patients with loco-regional recurrent breast carcinoma, and to assess its impact on the design of radiotherapeutic treatment.

METHODS AND MATERIALS

Between March 1991 and January 1997, 44 patients underwent thoracic CT examination with contrast material before the consideration of radiotherapy for their isolated loco-regional recurrent breast carcinoma. The CT radiographs were prospectively reviewed for additional findings clinically undetected by prior physical examination and plain-chest radiograph. The changes made in treatment design and dosage of radiation as a result of CT findings were recorded for analysis. The correlation between prognostic indicators and the CT findings was also studied.

RESULTS

Twenty-two of 44 (50%) patients were found to have additional abnormalities detected only after thoracic CT examinations were performed. The strategy of radiation therapy was altered in 17 of 22 (77%) patients as a result. Patients with shorter disease-free interval (p = 0.08) and multiple sites of recurrence (p = 0.05) tended to have greater numbers of findings on CT scan previously unsuspected. Thus, CT scan is a valuable guide to treating loco-regional recurrent disease.

CONCLUSION

Pretreatment diagnostic thoracic CT scan offers essential information that can alter treatment planning and thus optimize treatment strategy for a large proportion of patients with clinically isolated loco-regional recurrent breast carcinoma. In this population of patients we recommend that thoracic CT examination be considered before the initiation of radiation therapy.

Use of Modern Radiation Therapy Following Surgery for Invasive Breast Cancer

Radiation therapy has long been used in the treatment of breast cancer. However, it is still very difficult to state with certainty whether or not radiation therapy is truly beneficial for patients with breast cancer, mainly because breast cancers are very heterogeneous in their clinical behavior, and because radiation therapy has undergone significant change in the methodology. We extensively reviewed the literature, and determined that radiation therapy increases the survival of some patients, particularly in conjunction with surgery and systemic therapy. Although the total proportion of such patients seems to be small, appliedto the general population of breast cancer patients, the absolute number of women who might benefit from radiation therapy may be quite large.

The Role of Internal Mammary Lymph Node Metastases in the Management of Breast Cancer

We reviewed the literature regarding internal mammary lymph node metastasis in the management of breast cancer. Internal mammary dissection or radiotherapy provides no survival advantage in breast cancer patients. However, internal mammary nodal metastasis is an important independent prognostic factor. Patients with such metastases are candidates for systemic adjuvant hormonal therapy and/or chemotherapy. Moreover, in patients with histologically confirmed internal mammary metastases, irradiation of the nodes is appropriate for local control. Noninvasive techniques, such as internal mammary lymphoscintigraphy, parasternal sonography, computed tomography, and magnetic resonance imaging, are not satisfactory for the practical diagnosis of internal mammary metastasis. At present, biopsy of the internal mammary nodes in the first and second intercostal spaces is indicated for assessing nodal status and planning treatment.

Myocardial infarction among women with early-stage breast cancer treated with conservative surgery and breast irradiation

PURPOSE

To assess the possible impact of the irradiation on the risk of acute myocardial infarction among breast cancer patients treated with conservative surgery and postoperative radiation therapy.

METHODS AND MATERIALS

The incidence of and mortality from acute myocardial infarction was assessed in a group of 684 women with early-stage breast cancer diagnosed during 1976-1987 who had been treated with breast conserving surgery plus postoperative radiation therapy given with tangential photon fields. In 94% of the patients the total dose was between 48-52 Gy given with 2 Gy daily fractions 5 days per week for a total treatment period of about 4 1/2-5 1/2 weeks. In 88% of the patients the target volume included the breast parenchyma alone. In the remaining patients regional nodal areas were also irradiated. A concurrent group of 4,996 breast cancer patients treated with mastectomy without postoperative radiation therapy was used as a reference.

RESULTS

After a median follow-up of 9 years (range: 5-16 years) 12 conservatively treated patients (1.8%) had developed an acute myocardial infarction and 5 (0.7%) had died due to this disease. The age-adjusted relative hazard of acute myocardial infarction for the conservative group vs. the mastectomy group was 0.6 (95% C.I.: 0.4-1.2) and for death due to this disease 0.4 (0.2-1.1). The incidence of acute myocardial infarction among the conservatively treated women was similar irrespective of tumor laterality.

CONCLUSIONS

There was no indication of an increased risk of acute myocardial infarction with the radiation therapy among the women treated with conservative surgery. However, due to the small number of events the study could not exclude the possibility that cardiac problems may arise in some patients with left-sided cancers who have their heart located anteriorly in the mediastinum. Individual, three-dimensional dose planning represents one method to identify such patients and is basic to technical changes aimed at decreasing the cardiac radiation dose volume.

Prediction of excess risk of long-term cardiac mortality after radiotherapy of stage I breast cancer

BACKGROUND AND PURPOSE

Excess cardiac mortality has been reported in long-term follow up of breast cancer patients. Due to these findings it has been emphasized that radiotherapy techniques should be designed to minimize cardiac dose. The present study aims to provide risk figures of long-term excess cardiac mortality following radiotherapy for stage I breast cancer patients, using the relative seriality model. The impact of different modifications of the conventional irradiation technique on the calculated risk value is also analyzed.

MATERIAL AND METHODS

One hundred consecutive left-sided stage I breast cancer patients were selected. All patients were treated with post-operative radiotherapy, using tangential 6 MV photon beams. The dose planning of each patient was done by means of a three-dimensional dose planning system. The prescribed mean tumor dose was 50 Gy, 2 Gy/fraction, 5 days a week. For each dose plan the differential heart and myocardium dose-volume histogram (DVH) were calculated. The excess risk of late cardiac mortality was predicted for each patient with the relative seriality model, using a parameter set previously determined. Different methods to decrease the risk of excess cardiac mortality (conventional collimation vs. multileaf collimation (MLC), partial blocking of the target in order to spare the heart and finally a general fluence modulation method) were analyzed.

RESULTS AND CONCLUSIONS

The mean value of the calculated excess risk was 1.8%, having the heart as organ at risk, and 2.1% having the myocardium as organ at risk. However, a subgroup of patients where the risk increased up to about 9% (heart) and 12% (myocardium) was found. The risk could be substantially decreased either using an extended blocking of the target or applying the general fluence modulation method.

Radiotherapy of breast cancer after breast-conserving surgery: an improved technique using mixed electron-photon beams with a multileaf collimator

BACKGROUND AND PURPOSE

Loco-regional radiotherapy after breast cancer surgery significantly reduces the risk of recurrences. An increase of cardiac deaths for irradiated breast cancer patients has been reported in some studies, especially for women with tumours in the left breast. The aim of this study was to compare retrospectively the conventionally used technique using two opposed tangential photon beams with a modified technique using a combination of photon and electron beams to find an optimal technique with respect to dose homogeneity in the breast and surrounding regional lymph nodes and a minimal dose in the organs at risk.

MATERIALS AND METHODS

Thirty patients with stage II breast cancer who received different types of adjuvant systemic therapy were included in the investigation. Comparative dose planning of two techniques was performed, i.e. an isocentric technique with two photon beams with coplanar medial beam edges and a technique with one electron and three photon beams with a common isocentre for all beams aided by a multileaf collimator.

RESULTS

The mixed technique was selected for eight of 12 patients with left-sided breast cancers because of significantly lower doses to the heart. However, the decision-making was influenced by many factors such as dose coverage of the target volume combined with minimizing of the doses to the organs at risk and the contralateral breast.

CONCLUSION

The use of the mixed technique will optimize the loco-regional radiotherapy after breast-conserving surgery for many left-sided breast cancers.

Impact of respiratory maneuvers on cardiac volume within left-breast radiation portals

BACKGROUND

Late cardiac morbidity and mortality have been reported among left-breast cancer survivors treated with radiation therapy. Radiation-induced cardiotoxicity is affected by the volume of myocardium included in the radiation portals. We hypothesize that simple respiratory maneuvers may alter the position of the heart relative to the portals without altering the radiation dose delivered to the breast.

METHODS AND RESULTS

Fourteen healthy female adult volunteers underwent cardiac MRI to determine the cardiac volume included in the typical left-breast radiation field during respiratory maneuvers. Cardiac volume within the radiation portals was assessed from a transverse stack of 14 1-cm-thick contiguous slices covering the entire heart, obtained during breath holding at end-tidal volume (baseline), deep inspiration, and forced expiration. Thirteen subjects (92%) had inclusion of a portion of the heart within the radiation portals at end-tidal volume (median, 20.9 cm3; range, 1.3 to 88.4 cm3). In these subjects, inspiration decreased the cardiac volume included within the radiation portals (median change: -10.7 cm3 [-40.2%], P<.001 versus end-tidal volume), whereas expiration increased the cardiac volume included (median change: 4.0 cm3 [21.5%]; P<.001 versus end-tidal volume).

CONCLUSIONS

Inclusion of a portion of the heart in the left-breast radiation field is common. The use of simple inspiratory maneuvers significantly decreases cardiac volume within the radiation portals. Such an approach during delivery of radiation therapy may allow for preservation of radiation dosage to the breast while reducing cardiac involvement and subsequent mortality.

Loco-regional recurrence following mastectomy for early breast carcinoma: efficacy of radiotherapy at the time of recurrence

This study aims to define the risk factors for loco-regional relapse following mastectomy, and to assess the efficacy of radiotherapy at the time of relapse. To achieve this 272 patients with loco-regional relapse treated at a single institution with modified radical or radical mastectomy were reviewed. Tumour size, axillary node involvement and tumour grade were found to be significant risk factors for loco-regional recurrence of disease. Radiotherapy given at the time of relapse controlled disease in 61% of cases, compared with 34% of patients treated with systemic treatment only. Altogether, 146 (54%) of the 269 evaluable patients with local failure had uncontrolled disease at the same site, either at the time of death or at the date last seen. The result of this retrospective study showed that delayed radiotherapy was effective in controlling the disease in patients with developing loco-regional relapses. However, as adjuvant radiotherapy reduces the incidence of local disease recurrence it should be recommended to patients considered to be at high risk of local relapse following mastectomy; namely those with tumours bigger than 5 cm with four or more positive axillary nodes.

Hospital-related differences in breast cancer management. Analysis of an unselected population-based series of 1353 radically operated patients

A retrospective review is presented of 1353 consecutive patients with histopathologically confirmed invasive breast carcinoma treated radically with curative intent during the decade 1980-89. None had received adjuvant systemic therapy with hormones or prolonged chemotherapy. The distribution of lymph-node negative (N-) and lymph-node positive (N+) patients was 75% and 25%, respectively. The treatment and outcome were analysed as regards conventional prognostic parameters, in particular considering the axillary lymph-node status and the responsible hospital category (General Municipal Hospitals (MH)) versus Comprehensive Cancer Center (CC)). The most striking difference was detected as regards the number of examined lymph nodes. The median number of nodes described at the MH was 7, as compared to 14 at the CC (p < 0.001). In patients with pT1 tumours the highest rate of lymph-node positivity was observed when 10 or more axillary nodes were removed. Adjuvant radiotherapy reduced the loco-regional recurrence rate in the N-patients, whereas only the regional recurrences were reduced among the N+ patients. The five- and 10-year tumor-related survival rates were 86% and 76%, respectively, with no difference between the MH and the CC. As life-prolonging adjuvant hormone therapy and chemotherapy is now available for patients with axillary lymph node metastases, it is important that patients with breast cancer are operated adequately with the aim to remove at least 10 axillary lymph nodes. A thorough examination of the axillary content should be performed by the pathologist, and the number of resected lymph nodes and metastases should be reported. The establishment of nation-wide standard criteria for the management of breast cancer is recommended.

"One to three" or "four or more"?: selecting patients for postmastectomy radiation therapy

A review of randomized trials suggesting an improvement in overall patient survival with postmastectomy radiation therapy revealed that most patients in these studies had three or fewer positive axillary lymph nodes. Therefore, it is logical to consider using postmastectomy radiation therapy in all lymph node positive patients, not just those with four or more positive lymph nodes.

[Role of radiotherapy in the management of adenocarcinoma of the breast accessible to conservative surgery]

Standard treatment for limited stage adenocarcinoma of the breast includes lumpectomy (or a quadrantectomy), axillary node dissection, regional radiation therapy and, if the prognostic factors are unfavourable, chemotherapy and/or hormone therapy. This is supported by the results of American and European randomised trials. There have been many attempts at improving the modalities of conservative surgery and postoperative radiation therapy in order to maximize local control and minimize late sequellae. It is also likely that induction chemotherapy and external beam radiotherapy applied in selected cases increase the proportion of patients who can be offered conservative surgery.

Post-Operative Radiotherapy of the Rhabdomyosarcoma R1H of the Rat

Purpose. Post-operative radiotherapy (RT) is routinely applied in the treatment of several human tumours. The aim of the present study was to investigate the value of post-operative RT in a rat model.

Methods. Experiments were performed using the rhabdomyosarcoma R1H of the WAG/Rij rat. Animals were randomized to different treatment schedules: surgery, RT or a combination of both. Tumours were excised at different sizes (0.1–4.5 g) aiming for complete macroscopic resection. RT (60 Gy in 30 daily fractions over 6 weeks) was applied either primarily or to the former turnout site from the third post-operative day. Tumour growth delay, time to recurrence and local tumour control were used as endpoints.

Results. Pre-operative tumour size determined the time and rate of recurrence. The larger the tumour, the shorter the time to relapse and the higher the recurrence rate. The 50% local control rate (LCR₅₀) for surgery was found in tumours with a mass of 0.8 g. For post-operative RT a LCR₅₀ was achieved for tumours with a mass of 1.1 g. For larger turnouts (> 1.1 g), however, the rate and time course of relapse were similar for both the group receiving RT alone and the group receiving post-operative RT.

Discussion. In this model the tumour mass at excision governs the prognosis. Relatively small R1H turnouts may recur despite complete macroscopical resection. With regard to the LCR, the outcome for larger tumours is improved with post-operative RT (60 Gy/6 weeks) than compared with surgery alone. The factor is 1.3. Within a certain range of tumour sizes, combined treatment (surgery + RT) can improve the outcome considerably.

Myocardial damage in breast cancer patients treated with adjuvant radiotherapy: a prospective study

PURPOSE

To look for early and late signs of cardiac side effects of postoperative radiotherapy in patients with left-sided breast cancer.

METHODS AND MATERIALS

Seventeen left-sided primary (Stage I-III) breast cancer patients considered eligible were recruited. Their computer tomography-based dose planning showed a part of the heart's left ventricle irradiated with at least 85-95% of the total dose. Twelve patients were examined both before treatment and an average of 13 months later, at a first follow-up. In partially mastectomized patients tangential opposed photon fields were used to the breast tissue, while in patients with modified radical mastectomy electrons were given to the thorax. Echocardiography and a bicycle ergometry stress test with myocardial perfusion scintigraphy were carried out before and after radiotherapy to assess if any myocardial damage could be detected.

RESULTS

Six of the 12 patients exhibited new fixed scintigraphic defects after radiotherapy indicating regional hypoperfusion. Four of them received treatment only to the breast after breast-conserving surgery. The localization of the defects corresponded well with the irradiated volume of the left ventricle. No deterioration in left ventricular systolic or diastolic function could be detected by echocardiography.

CONCLUSIONS

In this study half of the patients exhibited new scintigraphic defects that indicate radiation-induced myocardial damage, probably affecting the microcirculation. There were no changes on electrocardiography or any deterioration of the left ventricular function at this stage. Long-term follow-up is necessary to assess whether this finding is a prognostic sign for developing radiation-induced coronary artery disease.

Fatal myocardial infarction potentially induced by paclitaxel

OBJECTIVE

To report a case of a fatal myocardial infarction (MI) possibly induced by paclitaxel in a patient with metastatic breast cancer.

CASE SUMMARY

A 67-year-old African-American woman with metastatic breast cancer was treated with a paclitaxel infusion. Fifteen hours into the 24-hour continuous infusion, the patient developed tachypnea, respiratory distress, and chest pain. Paciltaxel infusion was discontinued. Electrocardiogram findings revealed ST elevation in leads 2, 3, and aVF acutely. The cardiac enzymes were abnormal and the echocardiogram changes showed severe global left ventricular dysfunction consistent with acute MI. The patient died 13 hours after stopping the paclitaxel infusion.

DISCUSSION

Cardiac adverse effects of paclitaxel have been described in preliminary studies. Paclitaxel-induced cardiac abnormalities are usually described as asymptomatic and transient. MI secondary to paclitaxel infusion has rarely been reported. The mechanism by which paclitaxel causes cardiac abnormalities, especially myocardial damage, is not well understood.

CONCLUSIONS

Myocardial damage secondary to paclitaxel infusion is a serious and life-threatening adverse effect. Caution should be exercised in all patients treated with paclitaxel until more information regarding risk factors is available.

Long-term cardiac mortality after radiotherapy of breast cancer--application of the relative seriality model

Effects on the heart constitute a potentially significant and serious clinical problem in primary radiation therapy of early breast cancer. Increased cardiac mortality among irradiated patients may offset the potential benefit in terms of a reduced risk of recurrence or of death from breast cancer. Clinical data on long-term cardiac mortality among breast cancer patients included in two randomized trials (the Stockholm and Oslo studies) of radiation therapy as an adjunct to primary surgery were analysed using the relative seriality model of radiation response. Five different radiation therapy techniques were used in the trials. The original treatment plans were recalculated on a group of model patients using a three-dimensional treatment planning system. A mean dose-volume histogram (DVH) was calculated for each treatment technique. Both heart and myocardium, i.e. excluding circulating blood within the heart, were separately investigated as risk organs. Model parameters, (D50, i.e. the dose giving 50% complication probability; gamma, i.e. the maximum relative slope of the dose-response curve; s, describing the organ relative seriality) were determined by a chi 2 fitting of the calculated probability of excess cardiac mortality, based on the DVHs, to the incidence data. Computed complication probabilities for each treatment technique were modelled within the 95% confidence interval (CI) of the clinical incidence data. It was shown that the relative seriality model, assuming a homogeneous radiation sensitivity within the volume of the heart/myocardium can be used to describe the incidence data. A small dependence on the volume was found. The results do not, however, exclude the possibility that more sensitive structures within the myocardium are the main target for radiation.

Breast cancer

This synthesis of the literature on radiotherapy for breast cancer is based on 97 scientific articles, including 5 meta-analyses, 38 randomized studies, and 27 retrospective studies. These studies involve 387634 patients. Radiotherapy is the most effective method for preventing locoregional recurrence following primary surgery for invasive breast cancer, and radiotherapy is currently more effective than adjuvant chemotherapy after either mastectomy or breast-conserving surgery. Radiotherapy in patients at high risk for locoregional recurrence, eg, patients with spread to the axillary lymph nodes, leads to a significant increase in relapse free survival (eg, 1, 3). Meta-analyses have shown that radiotherapy in these subgroups of patients can reduce the risk for distant metastasis and reduce the risk for cancer death. These analyses have not statistically confirmed an improvement in total survival, probably because reduced mortality from breast cancer has been offset by increased mortality from cardiovascular disease. However, the results have successively improved, and survival gains are significantly greater in recent studies using modern treatment methods. It is probable that survival gains from radiotherapy do not exceed those that can be achieved by other adjuvant treatment of breast cancer such as chemotherapy or hormones, ie, a reduction in mortality by 20% to 30%, leading to an increased total survival after, eg, 10 years of 5% to 10%. The heart is the most important organ at risk during radiotherapy for breast cancer. Minimizing radiation doses to the heart muscle and the coronary arteries is necessary for avoiding later effects of ischemic cardiovascular disease. These side effects were particularly prominent in early treatment studies that used older radiotherapy methods. Radiotherapy in conjunction with breast-conserving surgery for invasive breast cancer significantly reduces the recurrence frequency in the breast. Clinical studies are under way that aim at further defining the role of radiotherapy as an element in a breast-conserving treatment strategy, e.g., determining the value of boost, and identifying prognostic/predictive factors for breast recurrence. Improved knowledge about such factors should eventually permit identification of patient groups at such low risk for breast recurrence that routine radiotherapy is unnecessary, or at such high risk-even with radiotherapy-that alternatives to breast conserving surgery should be considered. Radiotherapy also reduces the risk for recurrence in the breast following breast-conserving surgery of DCIS. Controlled trials are under way that aim at more closely defining the roles of surgical methods and radiotherapy for various subgroups of patients, eg, regarding different histopathologic types of DCIS. Radiotherapy has a substantial palliative value to patients who cannot be cured. It can reduce, prevent, or delay unpleasant symptoms from advanced disease, eg, pain, cancer lesions, fractures, neurologic symptoms. etc.

Effects of radiotherapy and surgery in early breast cancer. An overview of the randomized trials

BACKGROUND

Randomized trials of radiotherapy and surgery for early breast cancer may have been too small to detect differences in long-term survival and recurrence reliably. We therefore performed a systematic overview (meta-analysis) of the results of such trials.

METHODS

Information was sought on each subject from investigators who conducted trials that began before 1985 and that compared local therapies for early breast cancer. Data on mortality were available from 36 trials comparing radiotherapy plus surgery with the same type of surgery alone, 10 comparing more extensive surgery with less extensive surgery, and 18 comparing more extensive surgery with less extensive surgery plus radiotherapy. Information on mortality was available for 28,405 women (97.4 percent of the 29,175 women in the trials).

RESULTS

The addition of radiotherapy to surgery resulted in a rate of local recurrence that was three times lower than the rate with surgery alone, but there was no significant difference in 10-year survival; among a total of 17,273 women enrolled in such trials, mortality was 40.3 percent with radiotherapy and 41.4 percent without radiotherapy (P = 0.3). Radiotherapy was associated with a reduced risk of death due to breast cancer (odds ratio, 0.94; 95 percent confidence interval, 0.88 to 1.00; P = 0.03), which indicates that, after 10 years, there would be about 0 to 5 fewer deaths due to breast cancer per 100 women. However, there was an increased risk of death from other causes (odds ratio, 1.24; 95 percent confidence interval, 1.09 to 1.42; P = 0.002). This, together with the age-specific death rates, implies, after 10 years, a few extra deaths not due to breast cancer per 100 older women or per 1000 younger women. During the first decade or two after diagnosis, the excess in the rate of such deaths that was associated with radiotherapy was much greater women who were over 60 years of age at randomization (15.3 percent vs. 11.1 percent [339 vs. 249 deaths]) than among those under 50 (2.5 percent vs. 2.0 percent [62 vs. 49 deaths]). Breast-conserving surgery involved some risk of recurrence in the remaining tissue, but no significant differences in overall survival at 10 years were found in the studies of mastectomy versus breast-conserving surgery plus radiotherapy (4891 women), more extensive surgery versus less extensive surgery (4818 women), or axillary clearance versus radiotherapy as adjuncts to mastectomy (4370 women).

CONCLUSIONS

Some of the local therapies for breast cancer had substantially different effects on the rates of local recurrence--such as the reduced recurrence with the addition of radiotherapy to surgery--but there were no definite differences in overall survival at 10 years.

Tangential breast irradiation with or without internal mammary chain irradiation: results of a randomized trial

A prospective randomized study was made of 270 patients with unilateral stage I or II invasive breast cancer treated by segmental resection, axillary dissection and radiation at the University Hospital of Tampere, Finland, between 1989 and 1991. The aim of the study was to determine whether there is any advantage or disadvantage if the internal mammary chains (IMC) are included in the radiation target volume. The medial and lateral two-field technique was used and the target volumes were determined randomly either to include the internal mammary chain (IMC-RT) or not (no-IMC-RT). The prevalence of radiation pneumonitis was 16% and there was no significant difference between the IMC- and no-IMC-groups (18 vs. 14%). Skin reactions were equal in both groups. Lung fibrosis was more common in the IMC-RT group.

IN CONCLUSION

radiation of internal mammary chain after conservative surgery does not lead to an increase in clinically important skin or pulmonary complications. Whether it prevents recurrences or new primaries of the opposite breast is too early to say because of the short follow-up time.

Measuring irradiated lung and heart area in breast tangential fields using a simulator-based computerized tomography device

PURPOSE

To illustrate the use of a simulator based computerized tomography system (SIMCT) in the simulation and planning of tangential breast fields.

METHODS AND MATERIALS

Forty-five consecutive patients underwent treatment planning using a radiotherapy simulator with computerized tomography attachment. One to three scans were obtained for each patient, calculations were made on the central axis scan. Due to the wide aperture of this system all patients were able to be scanned in the desired treatment position with arm abducted 90 degrees. Using available software tools the area of lung and/or heart included within the tangential fields was calculated. The greatest perpendicular distance (GPD) from the chest wall to posterior field edge was also measured.

RESULTS

The mean GPD for the group was 25.40 mm with 71% of patients having GPDs of < or = 30 mm. The mean area of irradiated lung was 1780 sq mm which represented 18.0% of the total ipsilateral lung area seen in the central axis. Seven of the patients with left sided tumors had an average 1314 sq mm heart irradiated in the central axis. This represented 11.9% of total heart area in these patients.

CONCLUSIONS

Measurements of irradiated lung and heart area can be easily and accurately made using a SIMCT device. Such measurements may help identify those patients potentially at risk for lung or heart toxicity as a consequence of their treatment. A major advantage of this device is the ability to scan patients in the actual treatment position.

To treat or not to treat the internal mammary nodes: a possible compromise

PURPOSE

A method for designing partly wide tangential fields that irradiate the superiorly placed internal mammary nodes, yet exclude the inferiorly placed internal mammary nodes and the cardiac tissue, is described for patients receiving tangential radiation for breast cancer.

METHODS AND MATERIALS

Patients are immobilized in hemibody foam cradles. A CT study is performed with a series of fiducial markers. The CT data set can then either be transferred to the three-dimensional treatment planning computer for sophisticated treatment planning, or can be viewed to design partly wide tangential fields "by hand." This latter method is far less time consuming and, we believe, usually adequate, given the uncertainties in identifying the location of the internal mammary nodes.

RESULTS

This technique has been implemented in our clinic and has been used to treat approximately 15 patients. In four of these patients, a formal dose-volume histogram analysis revealed that these partly wide tangential fields can adequately exclude the cardiac volume and include the superiorly placed internal mammary nodes. Modest reductions in the pulmonary volume that is incidentally irradiated are seen compared to conventional wide tangents that irradiate the entire length of the internal mammary chain.

CONCLUSION

While controversy remains regarding the appropriateness of internal mammary nodal irradiation for patients with breast cancer, the technique described represents an attractive compromise. Selective irradiation of the superiorly placed internal mammary nodes (which are those at greatest risk for involvement) with customized "partly wide" tangential fields is possible. This treatment technique may provide the survival advantage that might be seen with internal mammary node irradiation, yet avoid the possible cardiac morbidity.

Postmastectomy radiotherapy in the management of operable breast cancer

There is a long and detailed history of radiation therapy as an adjuvant to surgery in operable breast cancer. The results of a large number of randomized clinical trials will be reviewed. They can be summarized by saying that although the trials show a reduction in local-regional failure with the use of postoperative radiotherapy, a survival advantage has not been clearly identified. Many of the older trials used techniques and radiation doses inadequate by current standards, which may have affected the results. Recent trials that used therapeutic doses of radiation, however, did demonstrate a survival advantage among patients who received postoperative radiotherapy. These trials generally have included chemotherapy and required careful integration of radiotherapy and systemic therapy. Although all trials have not demonstrated a survival benefit by the addition of radiotherapy, the ability to maintain local-regional control after mastectomy is an important goal. Administration of prophylactic chest wall and nodal radiotherapy to patients at high risk for local-regional recurrence significantly reduces the chance of a local treatment failure. Because a chest wall recurrence is a distressing event that dramatically affects quality of life, improved local-regional control with postoperative radiotherapy is a highly significant end point.

Morbidity of ischemic heart disease in early breast cancer 15-20 years after adjuvant radiotherapy

PURPOSE

To assess the cardiac side effects, primarily the occurrence of ischemic heart disease in symptom-free patients with early breast cancer treated with radiotherapy.

METHODS AND MATERIALS

Thirty-seven survivors of a former randomized study of early breast cancer were examined. Twenty patients irradiated pre- or postoperatively for left sided disease (study group patients) were compared with 17 controls who were either treated for right sided disease, or were nonirradiated patients. Radiotherapy was randomized in the original study; either tangential field 60Co, or electron-therapy was delivered. Echocardiography and bicycle ergometry stress test with 99mTc SestaMIBI myocardial perfusion scintigraphy were carried out and the patients' major risk factors for ischemic heart disease were also listed.

RESULTS

Our results showed a significant difference between the scintigraphic findings of the two groups. Five of the 20 study group patients (25%), while none of the 17 controls exhibited some kind of significant defects on scintigraphy, indicating ischemic heart disease (p < 0.05). No deterioration in left ventricular systolic and/or diastolic function could be detected by echocardiography.

CONCLUSION

Radiotherapy for left sided breast cancer with the mentioned treatment technique may present as an independent risk factor in the long-term development of ischemic heart disease, while left ventricular dysfunction could not be related to the previous irradiation. We emphasize the need to optimize adjuvant radiotherapy for early breast cancer by considering the dose both to the heart as well as the cancer.

Role of radiotherapy following total mastectomy in patients with early breast cancer. The Closed Trials Working Party of the CRC Breast Cancer Trials Group

Between June 1970 and April 1975 the CRC (King's/Cambridge) Trial for early breast cancer randomized 2800 patients following mastectomy to immediate prophylactic radiotherapy (DXT group, n = 1376) or control (WP group, n = 1424). Although no difference in overall survival has been demonstrated, there is an increase in mortality in the irradiated patients from nonbreast cancer causes beyond 5 years. It is because of an increase in the number of deaths due to new nonbreast malignancies [RR V 1.89 (1.18-3.05)] and to cardiac-related disease [RR = 1.52 (1.01-2.29)]. This increased cardiac death rate may be related to the use of orthovoltage, which has greater scatter. There was a significant increase in risk for those with left-sided rather than right-sided tumors in this subgroup [chi 2 (int) = 5.08; p = 0.02]. Local relapse was significantly reduced in those patients randomized to radiotherapy [RR = 0.44 (0.39-0.51)]. Median survival following local relapse was 1.35 years in the DXT group and 2.66 years in the WP group (logrank p < 0.001). Patients with the first relapse in the supraclavicular nodes had a particularly poor prognosis (median survival: DXT 0.69 years; WP 1.37 years). Almost 50% of patients who have had a recurrence on the chest wall or in the axilla and subsequently died have had disease at the same site at death, regardless of whether they had radiotherapy immediately following surgery. However, the actual number of patients dying with persistent disease is halved by the use of prophylactic radiotherapy (DXT 66; WP 143). Classic pathological features such as tumor size, tumor grade, and nodal involvement help define those patients at high risk of local failure who should be recommended for immediate radiotherapy.

Matching of electron and photon beams with a multi-leaf collimator

Multi-leaf collimators (MLCs) are offered as an accessory to many accelerators for radiation therapy. However, beam edges generated with these collimators are not as smooth as can be achieved with individually made blocks. The clinical drawbacks and benefits of this ripple were evaluated both for single field treatments and for combined adjacent fields of different beam qualities. In this investigation the MLC-collimated beams of the MM50 racetrack microtron were studied. The distance between the field edge and the 90% isodose was measured at the reference depth for four beam qualities (20 MV photons and 10, 20 and 50 MeV electrons). This distance was found to vary from approximately 6 mm for straight beam edges (i.e., all collimator leaves aligned) to approximately 2 mm from the tip of the leaves for a saw-tooth shaped beam edge. The over- and under-dosage in the joint between combined adjacent fields was found to be typically +/- 10% in small volumes. Improved clinical techniques using adjacent photon and electron fields with the same isocentre and source position (without moving the gantry) have been developed. For treatments of the breast, including the mammary chain, a uniform dose distribution was created with special attention given to the irradiation of the heart and lung outside the target volume. A method for head and neck treatments was optimised to give uniform dose distribution in the joint between the photon and electron fields and a method of treating the mediastinum, including the chest wall in front of the left lung, was analysed with respect to dose uniformity in the tumour and shielding of the lung.