The radiation dose-response relationship for control of primary breast cancer

Factors influencing pathological complete response and tumor regression in neoadjuvant radiotherapy and chemotherapy for high-risk breast cancer

BACKGROUND

Pathological complete response (pCR) is a well-established prognostic factor in breast cancer treated with neoadjuvant systemic therapy (naST). The determining factors of pCR are known to be intrinsic subtype, proliferation index, grading, clinical tumor and nodal stage as well as type of systemic therapy. The addition of neoadjuvant radiotherapy (naRT) to this paradigm might improve response, freedom from disease, toxicity and cosmetic outcome compared to adjuvant radiotherapy. The factors for pCR and primary tumor regression when neoadjuvant radiation therapy is added to chemotherapy have not been thoroughly described.

METHODS

We performed a retrospective analysis of 341 patients (cT1-cT4/cN0-N+) treated with naRT and naST between 1990 and 2003. Patients underwent naRT to the breast and mostly to the supra-/infraclavicular lymph nodes combined with an electron or brachytherapy boost. NaST was given either sequentially or simultaneously to naRT using different regimens. We used the univariate and multivariate regression analysis to estimate the effect of different subgroups and treatment modalities on pCR (ypT0/Tis and ypN0) as well as complete primary tumor response (ypT0/Tis; bpCR) in our cohort. Receiver operating characteristic (ROC) analysis was performed to evaluate the interval between radiotherapy (RT) and resection (Rx) as well as radiotherapy dose.

RESULTS

Out of 341 patients, pCR and pbCR were achieved in 31% and 39%, respectively. pCR rate was influenced by resection type, breast cancer subtype, primary tumor stage and interval from radiation to surgery in the multivariate analysis. Univariate analysis of bpCR showed age, resection type, breast cancer subtype, clinical tumor stage and grading as significant factors. Resection type, subtype and clinical tumor stage remained significant in multivariate analysis. Radiation dose to the tumor and interval from radiation to surgery were not significant factors for pCR. However, when treatment factors were added to the model, a longer interval from radiotherapy to resection was a significant predictor for pCR.

CONCLUSIONS

The factors associated with pCR following naST and naRT are similar to known factors after naST alone. Longer interval to surgery might to be associated with higher pCR rates. Dose escalation beyond 60 Gy did not result in higher response rates.

Optimising of axillary therapy in breast cancer: lessons from the past to plan for a better future

In this narrative review, we aim to explore the ability of radiation therapy to eradicate breast cancer regional node metastasis. It is a journey through data of older trials without systemic therapy showing the magnitude of axillary therapy (surgery versus radiation) on cancer control. Considering that both systemic and loco-regional therapies were shown to reduce any recurrence with a complex interaction, our review includes surgical, radiation, and radiobiology consideration for breast cancer, and provide our view of future practise. The aim is to provide information optimise radiation therapy in the era of primary systemic therapy.

Computed tomography-based virtual simulation versus ultrasound-based clinical setup in electron breast boost radiotherapy: Methodology for CT-based electron virtual simulation

PURPOSE

To compare clinical setup using ultrasound (U/S)-delineated target versus computed tomography (CT) virtual simulation using CT-outlined target in breast electron boost. To describe a methodology for electron virtual simulation and collision testing with the treatment planning system (TPS).

METHODS

The two techniques were compared in a prospective study on 12 patients, who were treated using a clinical setup. Target definition was performed by both U/S and CT imaging. The U/S-based target was made visible on CT images by placing a radio-opaque wire on U/S skin markings. The dose distribution of the clinical setup was reproduced in the TPS using the actual electron patient treatment parameters. A CT-based TPS virtual simulation/dose optimization was compared to the clinical setup technique.

RESULTS

Mean beam aperture was larger by 16.3 cm² (p = 0.011) for U/S compared to CT-outlined target. Target mean depth difference (CT minus U/S) was 0.03 cm (p = 0.875). Target coverage at depth was adequate in all cases with CT-based simulation while under/overcovering the target at depth by more than 5 mm in 2 out of 12 cases with clinical setup. Mean target V_90% was 98.5% (CT-based simulation) and 84.4% (clinical setup). Ipsilateral lung/breast were better spared with CT-based simulation. To date, the methodology for CT virtual simulation was applied on 152 patients and collision was avoided in all cases.

CONCLUSIONS

CT-based simulation and target delineation allows for improved definition of the en-face electron field with less amount of normal tissue irradiated while including the entire target with an adequate margin and optimal electron energy.

Hypofractionated Whole-Breast Irradiation With or Without Boost in Elderly Patients: Clinical Evaluation of an Italian Experience

PURPOSE

To examine local control, disease-free survival (DFS), and toxicity in elderly (≥ 65 years) breast cancer patients treated with hypofractionated radiotherapy (hypo-RT) with or without a boost to the tumor bed.

PATIENTS AND METHODS

The study was conducted on 752 patients treated from April 2009 to February 2017. Patients received 42.4 Gy in 16 daily fractions (2.65 Gy per fraction). A boost was only administered in cases of grade 3 primary tumor and close or positive margins. Acute and late toxicity was prospectively assessed during and after hypo-RT, based on the Radiation Therapy Oncology Group scale. DFS and local recurrence-free survival were estimated by the Kaplan-Meier method for cumulative probability. Log-rank tests were used to identify differences by subtype. Cox proportional hazard models were used to investigate the impact of various factors on the risk of disease progression.

RESULTS

Among the 752 patients treated, 41 (5.5%) experienced disease progression, including 7 (17.1%) exclusively local recurrences; 1 (2.4%) local and nodal recurrence; 1 (2.4%) local and nodal recurrence plus metastasis; 7 (17.1%) nodal recurrences plus metastases; and 25 (61%) exclusively distant metastases. The 5-year DFS, local recurrence-free survival, breast cancer-specific survival, and overall survival rates were 91.8% (95% confidence interval [CI], 88.6-94.2), 98.0% (95% CI, 96.1-99.1), 98.2% (95% CI, 96.5-99.1), and 87.5% (95% CI, 83.8-90.5), respectively. On univariate analysis, the administration of a boost, disease grade (grades 1 and 2 vs. 3), and molecular subtype (triple negative or human epidermal growth factor receptor 2 [HER2] positive, or luminal B vs. luminal A) significantly affected disease progression (P < .01). These findings were confirmed by multivariate analysis.

CONCLUSION

Hypo-RT is effective and well tolerated in the elderly population, and the routine use of a boost for patients over 65 years is not justified. Further studies on the boost issue are strongly advocated.

Tumor Bed Boost Integration during Whole Breast Radiotherapy: A Review of the Current Evidence

Radiation therapy delivered with hypofractionation, which involves the delivery of a higher dose per fraction in fewer fractions (generally with a lower total nominal dose) over a shorter overall treatment time, is an established therapeutic option at least for a selected group of early breast cancer patients after breast-conserving surgery. Optimal delivery of the tumor bed boost dose in terms of timing, fractionation, and total dose whenever a hypofractionated schedule is employed has yet to be established. We herein present a review of the current evidence on the role of boost integration in whole breast radiotherapy.

Quality assurance in breast cancer: EORTC experiences in the phase III trial on irradiation of the internal mammary nodes

The EORTC 22922/10925 trial randomly compares irradiation or no irradiation of the internal mammary and medio supraclavicular (IM-MS) nodes for stage I-III breast cancer. We report on the characteristics of 4004 participating patients, aspects of quality assurance and compliance to protocol treatment. The actual population has intermediate-risk disease: 51.8% stage II, 56% positive axillary nodes. The allocated treatment was not followed in 3.2% in the IM-MS irradiation arm versus 2% in the no IM-MS irradiation arm. In the IM-MS arm, there were major deviations for dose in 0.8%, surgery-to-radiotherapy time interval in 3.9% and in overall treatment time in 0.9% cases. Major deviations were found in 7.9% patients in the IM-MS group and in 2% patients in the no IM-MS group. In the final trial analysis, a sensitivity analysis should evaluate the subgroup of patients receiving an optimal treatment to verify the robustness of the results and the true impact of IM-MS irradiation.

Recent Advances in Radiation Therapy for Head and Neck Cancer

The treatment of locally advanced or recurrent head and neck cancers has improved from single modality interventions of surgery and radiation therapy alone to include combined modality therapy with surgery, chemotherapy and radiation. Combined therapy has led to improved local control and disease-free survival. New developments in radiation oncology such as altered fractionation, three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, stereotactic radiosurgery, fractionated stereotactic radiotherapy, charged-particle radiotherapy, neutron-beam radiotherapy, and brachytherapy have helped to improve this outlook even further. These recent advances allow for a higher dose to be delivered to the tumor while minimizing the dose delivered to the surrounding normal tissue. This article provides an update of the new developments in radiotherapy in the management of head and neck cancers.

Placing the boost in breast-conservation radiotherapy: A review of the role, indications and techniques for breast-boost radiotherapy

Randomised trials have established that the addition of a boost dose of radiotherapy to the lumpectomy site after whole-breast adjuvant radiotherapy further improves local control achieved by whole-breast radiotherapy alone. The absolute size of this benefit varies according to the baseline risk of local recurrence. Age is the strongest predictor of benefit. Below the age of 40 years, the absolute benefit of a boost seems to be substantial, and there are no clearly identified groups unlikely to benefit. Above the age of 50 years, the benefit is small, and several additional risk factors for local failure would need to be present to merit boost treatment. These may include tumour size, high grade, high mitotic rate, lymphovascular invasion, extensive and high grade associated with intraduct carcinoma, receptor-positive tumours when avoidance of anti-oestrogen therapy is desired or receptor-negative tumours. Other independent reasonable indications for the use of a boost would be positive margins where further surgery is not indicated. If a boost is indicated, a variety of techniques may be used and toxicity and cosmetic results remain highly acceptable. Overall, there seems to be no substantial differences in boost technique results; however, interstitial techniques may have advantages for deeper targets compared with electrons. Irrespective of technique, accurate localisation will maximise the benefit of a boost. Surgical clips are strongly recommended to facilitate localisation.

Radiobiology of Breast Cancer

Advances in molecular and cellular biology are transforming our understanding of breast cancer and promise the same for radiotherapy over the next few years. At the clinical level, the molecular basis of fractionation dependency and other tumour and normal tissue responses are likely to become clearer. More importantly, they will become useful in the clinic, where molecular characterisation of the patient and tumour will start to determine therapeutic options. Although many of the fundamental processes are only amenable to study in laboratory systems, the power of array-based technologies makes it possibly to address highly relevant questions in the clinic, using functional imaging and/or tissue biopsies. To help clinical oncologists exploit these opportunities in translational research, some aspects of the molecular and cellular basis of radiotherapy are described below in their relation to breast cancer.

Survival Effects of Postmastectomy Adjuvant Radiation Therapy Using Biologically Equivalent Doses: A Clinical Perspective

BACKGROUND

Postmastectomy radiation therapy reduces locoregional recurrence among women with operable breast cancer, but whether it improves survival has been controversial. We reanalyzed the results from 36 unconfounded trials (i.e., addition of radiation therapy was the sole discriminant between treatments being compared) that were identified in previous meta-analyses, which provided 38 comparisons.

METHODS

We used three predefined treatment categories for individual patient data: 1) a biologically equivalent dose (BED) of 40-60 Gy in 2-Gy fractions with an appropriate target volume, 2) an inadequate or excessive dose of radiation therapy, and 3) an inappropriate target volume. Effects of radiation therapy on 5-year and 10-year survival in each of the treatment categories were estimated from a cohort of 13 199 patients from the published rates or, if these were unavailable, from the published survival curves. We also used this categorization to reanalyze data from Early Breast Cancer Trialists' Collaborative Group (EBCTCG) postmastectomy studies. At 10 years, 16 (84%) of the 19 comparisons in our study coincided with those reported by the EBCTCG. All statistical tests were two-sided.

RESULTS

Twenty-five of the 38 available comparisons had used optimal and complete radiotherapy (i.e., category 1). Of these 25 comparisons, 17 had 5-year data, and these data showed that adjuvant radiation therapy was associated with a 2.9% absolute increase in survival (odds ratio [OR] of death = 0.87, 95% confidence interval [CI] = 0.79 to 0.96; P = .006). Thirteen category 1 trials had data at 10 years, and these data showed that adjuvant radiation therapy was associated with a statistically significant 6.4% absolute increase in survival (OR of death = 0.78, 95% CI = 0.70 to 0.85; P < .001). No statistically significant change in survival was observed among category 2 (OR of death = 0.91, 95% CI = 0.75 to 1.11) or 3 (OR of death = 0.97, 95% CI = 0.61 to 1.55) trials. Among the 33 EBCTCG studies, odds of local recurrence were reduced more among category 1 trials (80% lower) than among category 2 (70% lower) or 3 (64% lower) trials (P(heterogeneity) < .001). Odds of all-cause death were also lower among category 1 trials (13% lower) than among category 2 (3% lower) or 3 (26% higher) trials (P(heterogeneity) = .01).

CONCLUSIONS

Adjuvant radiation therapy with an optimal BED and target volume was statistically significantly associated with improved survival for up to 10 years.

Biologic comparison of partial breast irradiation protocols

PURPOSE

To analyze the dose/fractionation schedules currently used in ongoing clinical trials of partial breast irradiation (PBI) by comparing their biologically effective dose (BED) values to those of three standard whole breast protocols commonly used after segmental mastectomy in the treatment of breast cancer.

METHODS AND MATERIALS

The BED equation derived from the linear-quadratic model for radiation-induced cell killing was used to calculate the BEDs for three commonly used whole breast radiotherapy regimens, in addition to a variety of external beam radiotherapy, as well as high-dose-rate and low-dose-rate brachytherapy, PBI protocols.

RESULTS

The BED values of most PBI protocols resulted in tumor control BEDs roughly equivalent to a 50-Gy standard treatment, but consistently lower than the BEDs for regimens in which the tumor bed receives a total dose of either 60 Gy or 66 Gy. The BED values calculated for the acute radiation responses of erythema and desquamation were nearly all lower for the PBI schedules, and the late-response BEDs for most PBI regimens were in a similar range to the BEDs for the standard treatments.

CONCLUSION

Biologically effective dose modeling raises the concern that inadequate doses might be delivered by PBI to ensure optimal in-field tumor control.

The influence of the boost technique on local control in breast conserving treatment in the EORTC 'boost versus no boost' randomised trial

BACKGROUND AND PURPOSE

The EORTC Trial 22881/10882 investigating the role of a boost dose in breast conserving therapy demonstrated a significantly better local control rate with the higher radiotherapy dose, especially in women younger than 50 years of age. This paper investigates the potential impact of the different boost techniques on local control and on fibrosis after breast conserving therapy.

PATIENTS AND METHODS

From 1989 to 1996, 2661 patients were randomised to receive a boost dose of 16Gy to the primary tumour bed after microscopically complete tumorectomy and 50Gy whole breast irradiation. The choice of the boost technique was left to the treating investigator. Treatment data were prospectively recorded as well as the clinical outcome in terms of local control and fibrosis. Sixty-three percent of the patients received a boost dose with fast electrons, 28% with photon beams and 9% with interstitial brachytherapy.

RESULTS

At 5 years, local recurrences were seen in 74 of the 1635 patients who received an electron boost (4.8%, CI 3.6-5.9%), in 28 of the 753 patients who received a photon boost (4.0%, CI 3.4-5.5%) and in 6 of the 225 patients after an interstitial boost (2.5%, CI 0.3-4.6%). The grade of fibrosis in the whole breast as well as at the primary tumour bed, as scored by the treating radiation oncologist, was similar in the three groups.

CONCLUSIONS

Although the three groups are of a rather unequal size, the results of the interstitial boost seem similar in terms of fibrosis and at least as good in terms of local control, despite a lower treatment volume and a longer overall treatment time.

Why a breast boost should remain a controversial aspect of routine breast conservation management in Australia and New Zealand in 2002

Two randomized trials have recently shown a statistically significant improvement in local control when a boost is employed in the conservative treatment of early breast cancer. However, unresolved issues of cost effectiveness, potentially increased toxicity and the inability to automatically generalize these results to Australian and New Zealand practice remain. In view of these unresolved controversies, the St George and Wollongong hospitals breast boost trial (SGW trial) will continue to recruit.

The role of radiotherapy in rectal cancer

In Europe, short-term radiotherapy is increasingly used in the primary management of rectal cancer. In the United States, postoperative chemoradiotherapy is the standard treatment of choice. The rationale and indications for radiotherapy and possible combinations with chemotherapy are discussed and an overview of all of the randomised trials containing radiotherapy as one randomisation arm is given. Three major indications for radiotherapy can be identified: the reduction of local recurrences in mobile rectal cancer, downstaging of the tumour in primary irresectable tumours and downsizing of low-lying tumours in attempts to more frequently perform a sphincter-saving procedure. For reduction of local recurrences, radiotherapy can be given either pre- or postoperatively, although preoperative therapy is more dose-efficient. Short-term preoperative radiotherapy reduces the number of recurrences and improves survival. Improved survival is also reported after postoperative radiotherapy in combination with chemotherapy, however, the relevance of the radiotherapy component is discussed. Although the debate about radiotherapy is still ongoing, we strongly believe that the results demonstrate that short-term preoperative radiotherapy is the treatment of choice for resectable rectal cancer.

Adjuvant radiotherapy in breast cancer--the treatment of lymph node areas

Adjuvant radiotherapy decreases the risk of locoregional recurrences threefold, according to the results of many randomized trials and overviews. In patients treated with total mastectomy, the risk of local recurrence is mainly related to the number of involved axillary nodes, i.e. about 25%, 35% and 55% at 10 years when 1-3, 4-9 and 10 or more nodes are involved, respectively. In contrast, at 10 years, less than 15% of patients with negative axillary nodes relapse locally. The effect of adjuvant radiotherapy on distant metastases and overall survival is a controversial issue. On the one hand, recent results are compatible with the existence of a mechanism of secondary dissemination generated from locoregional tumor nests. The beneficial effect of radiotherapy can be observed whether with or without adjuvant systemic treatment. On the other hand, a deleterious late toxic effect, mainly cardiac, has also been shown. The importance of improvements in radiation techniques and quality assurance to obtain a positive balance in terms of overall survival is emphasized.

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.

Perioperative radiotherapy in rectal cancer

Local failure of rectal cancer is one of the principal causes of morbidity and mortality. In order to lower unacceptably high local failure rates, pre- or postoperative radiotherapy has been extensively investigated. The collected information from all controlled trials reported so far shows that the proportion of local recurrences is reduced to less than half when radiotherapy up to moderately high doses is given preoperatively. This reduction is smaller after postoperative radiotherapy, even if higher doses are used. In addition, there is a positive influence on survival from preoperative radiotherapy. Improved survival has also been seen in trials using postoperative radiotherapy, but only when combined with chemotherapy. With proper radiation techniques, sufficiently high doses can be given preoperatively with little, if any, increase in postoperative mortality and morbidity. Furthermore, late toxicity can be anticipated to be low provided the technique is optimal. The beneficial effects noted so far have been achieved in trials where 'standard' surgery has been used, followed by a local recurrence rate of more than 20% (average 29%, range 23-46%) of the patients. It is, however, possible that the reduction in local failure rates is proportionally even greater added to 'optimal' surgery, although the absolute number of failures prevented is lower.

Patterns of dose variability in radiation prescription of breast cancer

PURPOSE

Comparison of radiation outcome of various treatment protocols is difficult due to the variability of dose prescription. A retrospective analysis of the pattern and intercomparison of dose prescriptions is presented for the treatment of breast cancer.

MATERIALS AND METHODS

To represent the clinical practice for breast irradiation with tangential fields, commonly used prescription points were chosen that lie on the perpendicular bisector of the chest wall separation (s) that represents the breast apex height (h). These points are located at 1.5 cm from the posterior beam edge, at the chest wall-lung interface (2-3 cm), at distances of h/3 and h/2, and at the isocenter. One hundred consecutive patients treated with intact breast following excisional biopsy were used in this study. For analysis, treatment planning was carried out without lung correction with a 6 MV beam for all patients, even though some of the patients were treated with high energy beams for dose uniformity. Dose distributions were optimized with wedges and beam weights to provide a symmetrical dose distribution on the central axis plane. The statistical analyses of the different parameters, s, h, maximum dose, and doses at various prescription points were carried out.

RESULTS

The maximum dose (hot spot) in breast varied from +5% to +27% above the prescribed dose among the patient population. The hot spot was directly related to s, and appeared to be independent of h and the ratio h/s. Among 55%, 40%, and 5% of the patients, the magnitude of the hot spot was 5-10%, 10-15%, and >15%, respectively. Except for the magnitude of the hot spot, the doses at various prescription points were independent of the breast size. For a prescription point at h/3 or at the lung-chest wall interface, the dose variation within +/- 1% is observed for 90% of the patient population. On the other hand, the average dose variation is about +/- 3% among other protocols with dose prescription point varying up to the h/2 point. With the prescription point at the isocenter, an average and maximum variation of 4-5% and 11% were observed, respectively. The maximum dose inhomogeneity for some patients was significantly higher, i.e. up to +27% even without the lung correction.

CONCLUSIONS

A wide variation in prescription dose is observed among the different treatment protocols commonly used in breast treatment. For a total dose of 46-50 Gy delivered at 2 Gy/fraction to the breast, the prescribed dose may vary between 50 and 55 Gy and the hot spot dose per fraction may range between 2.3 and 2.5 Gy depending on the protocol and breast size. Thus dose normalization at hot spot and the isocenter should be discouraged unless the total dose to the breast is modified. A uniform definition of dose prescription for breast treatment is greatly required for intercomparison of clinical data.

Radiotherapy in addition to radical surgery in rectal cancer: evidence for a dose-response effect favoring preoperative treatment

PURPOSE

This study explored the relationship between radiation dose and reduction in local recurrence rate after preoperative and postoperative radiotherapy in rectal cancer.

METHODS AND MATERIALS

All randomized trials initiated prior to 1988 comparing preoperative and postoperative radiotherapy with surgery alone or with each other were included. Local failure rates were available in 5626 randomized patients. The linear quadratic formula was used to compensate for different radiotherapy schedules.

RESULTS

For preoperative radiotherapy, a clear dose-response relationship could be established. For postoperative radiotherapy, the range of doses was narrow, and a dose-response relationship could not be demonstrated. At similar doses, preoperative radiotherapy appeared to be more efficient in reducing local failure rate than postoperative. The only trial comparing preoperative with postoperative radiotherapy confirms this notion. A 15-20 Gy higher dose may be required postoperatively than preoperatively to reach similar efficacy. Neither approach alone significantly influences survival, although it is likely that a small survival benefit may be seen after preoperative radiotherapy.

CONCLUSIONS

The information from the entire randomized experience suggests that preoperative radiotherapy may be more dose efficient than postoperative radiotherapy.

Recent advances in radiation oncology

Radiotherapy remains an important component of the management of malignant disease. Especially when combined with cytotoxic chemotherapy, limited surgical excision, or both, irradiation has been shown to control disease in the primary site and regional nodes without the need for surgical extirpation as frequently as in past years. New developments in three-dimensional treatment planning and the precise delivery of high-dose radiation promise to increase the benefit of radiation treatment. Finally, molecular studies of the cell's response to radiation and the phenomena of DNA damage and repair are providing explanations for heretofore unexplained radiobiologic observations. Such research is laying the groundwork for targeted manipulation of the cell's response to radiation, which will be tested in the near future.

The role of radiotherapy in breast conserving treatment

Radiotherapy in breast conserving procedures is instrumental for reducing the frequency of a breast relapse, and may even improve survival. The treatment can be associated with morbidity, that is not negligible. A high-quality technique is needed in order to achieve an optimal therapeutic ratio.

Long-term effects of adjuvant tamoxifen and/or radiotherapy. The South Sweden Breast Cancer Trial

In a multicenter trial of adjuvant therapy in stage II breast cancer, 719 postmenopausal patients were randomized to one of three treatment regimens: radiotherapy only or in combination with adjuvant tamoxifen for one year, or adjuvant tamoxifen without radiotherapy. At twelve years of follow-up (median 9 years), no statistically significant differences in survival or recurrence-free survival were observed. However, the rate of loco-regional recurrency was lower among patients treated with both radiotherapy and tamoxifen. The rate of bilateral breast cancer was reduced in tamoxifen-treated patients whereas the rate of new primary malignancies other than breast cancer was somewhat higher in tamoxifen-treated patients. Adjuvant therapy in breast cancer may influence not only breast cancer recurrences and mortality but also later disease patterns and cause-specific mortality.

Alternating radiotherapy and chemotherapy in non-metastatic inflammatory breast cancer

Ninety-nine patients presenting with non-metastatic inflammatory breast cancer were treated with an alternating protocol of radiotherapy and chemotherapy. The alternating schedule consisted of 8 courses of combined chemotherapy, including doxorubicin, vincristine, cyclophosphamide, methotrexate and 5-Fluorouracil, and 3 series of loco-regional radiotherapy delivering a total dose of 65 to 75 Gy to the breast tumor, 65 Gy to the axilla, and 50 Gy to the supraclavicular and internal mammary chain lymph nodes. Radiotherapy was started after the third course of chemotherapy. A 1-week gap was respected between each course of chemotherapy and each series of radiotherapy. Seventy-five percent of patients were in complete remission at the end of this induction treatment. The 3-year local control was 72% and the 3-year overall survival rate was 70%. An isolated local recurrence was observed in only 4% of patients. Approximately one-half of patients developed distant metastases. These results show that alternating radiotherapy and chemotherapy schedules deserve further investigation in locally advanced breast cancer.

Intraoperative Ir-192 implantation for early breast cancer. Techniques and results

Patients with early breast cancer (T1-2 N0-1) can be treated by lumpectomy and irradiation with a local control and survival equal to more radical surgery. Between 1982 and 1988, 323 patients with early breast cancer were treated, when possible, with Ir-192 implants at the time of lumpectomy to a local dose of 2000 cGy in 40-50 hours. Ten to 14 days later, the whole breast was treated to 4500 cGy at 180 per fraction in 5 weeks. The 6-year actuarial survival for stages I and II disease was 98% and 91%, respectively, and the recurrence-free survival was 96% and 98%, respectively. When these 323 patients were evaluated by T status, a local control of 97% was the same for T1 and T2 lesions. The cosmetic results were good to excellent in 95% of the patients. This approach has improved our ability to accurately place the boost dose in the breast.

Thermoradiotherapy of primary breast carcinoma

Since 1981, 40 patients with advanced breast carcinoma have been treated with megavoltage radiotherapy combined with hyperthermia. The irradiation dose to the primary tumour was 50 Gy/25 fractions, five fractions per week. Hyperthermia (aim: 44 degrees C/30 min) was applied once a week, 30 minutes after the midweek radiation fraction. Tumour response did not correlate with the chance of long-term local control. The likelihood of 3-year local control was 46 per cent and 3-year survival was 52 per cent. The local tumour control rate decreased with increasing T stage and was related to non-uniformity of the temperature distribution in the heated volume. It was concluded that (a) the radiation dose should be increased and (b) the temperature uniformity should be improved.

An approach to the interpretation of clinical data on the tumour control probability-dose relationship

A conventional statistical model allows predicting the sterilisation rate as a function of dose. However, the computation requires data on biological parameters (proportion of clonogenic cells, survival per fraction, multiplication rate) which are inaccessible for human tumours. The curative dose 50% (TCD50) can be used as a synthesis of these parameters and its significance for the response-dose relationship of a population of tumours of uniform radiosensitivity is discussed. The slope of the dose-control curve provides vital information regarding the variation in radiocurability of the various individual tumours. The model allows the analysis of the clinical data and the separation of tumour subsets with different radiation responsiveness. It provides an evaluation of the benefit which could be obtained from the identification of the subsets and a guidance for the clinical, pathological and biological studies which relate to this identification. The change in the response-dose relationships with the tumour size cannot (usually) be explained by the cell number increase alone. Other possible factors of reduced radiocurability are discussed.