The Cancer Research Campaign (King's/Cambridge) trial for early breast cancer: an analysis of the radiotherapy data

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.

Fraction size in radiation therapy for breast conservation in early breast cancer

BACKGROUND

Shortening the duration of radiation therapy would benefit women with early breast cancer treated with breast conserving surgery. It may also improve access to radiation therapy by improving efficiency in radiation oncology departments globally. This can only happen if the shorter treatment is as effective and safe as conventional radiation therapy. This is an update of a Cochrane Review first published in 2008 and updated in 2009.

OBJECTIVES

To assess the effect of altered radiation fraction size for women with early breast cancer who have had breast conserving surgery.

SEARCH METHODS

We searched the Cochrane Breast Cancer Specialised Register (23 May 2015), CENTRAL (The Cochrane Library 2015, Issue 4), MEDLINE (Jan 1996 to May 2015), EMBASE (Jan 1980 to May 2015), the WHO International Clinical Trials Registry Platform (ICTRP) search portal (June 2010 to May 2015) and ClinicalTrials.gov (16 April 2015), reference lists of articles and relevant conference proceedings. No language or publication constraints were applied.

SELECTION CRITERIA

Randomised controlled trials of altered fraction size versus conventional fractionation for radiation therapy in women with early breast cancer who had undergone breast conserving surgery.

DATA COLLECTION AND ANALYSIS

Two authors performed data extraction independently, with disagreements resolved by discussion. We sought missing data from trial authors.

MAIN RESULTS

We studied 8228 women in nine studies. Eight out of nine studies were at low or unclear risk of bias. Altered fraction size (delivering radiation therapy in larger amounts each day but over fewer days than with conventional fractionation) did not have a clinically meaningful effect on: local recurrence-free survival (Hazard Ratio (HR) 0.94, 95% CI 0.77 to 1.15, 7095 women, four studies, high-quality evidence), cosmetic outcome (Risk ratio (RR) 0.90, 95% CI 0.81 to 1.01, 2103 women, four studies, high-quality evidence) or overall survival (HR 0.91, 95% CI 0.80 to 1.03, 5685 women, three studies, high-quality evidence). Acute radiation skin toxicity (RR 0.32, 95% CI 0.22 to 0.45, 357 women, two studies) was reduced with altered fraction size. Late radiation subcutaneous toxicity did not differ with altered fraction size (RR 0.93, 95% CI 0.83 to 1.05, 5130 women, four studies, high-quality evidence). Breast cancer-specific survival (HR 0.91, 95% CI 0.78 to 1.06, 5685 women, three studies, high quality evidence) and relapse-free survival (HR 0.93, 95% CI 0.82 to 1.05, 5685 women, three studies, moderate-quality evidence) did not differ with altered fraction size. We found no data for mastectomy rate. Altered fraction size was associated with less patient-reported (P < 0.001) and physician-reported (P = 0.009) fatigue at six months (287 women, one study). We found no difference in the issue of altered fractionation for patient-reported outcomes of: physical well-being (P = 0.46), functional well-being (P = 0.38), emotional well-being (P = 0.58), social well-being (P = 0.32), breast cancer concerns (P = 0.94; 287 women, one study). We found no data with respect to costs.

AUTHORS' CONCLUSIONS

We found that using altered fraction size regimens (greater than 2 Gy per fraction) does not have a clinically meaningful effect on local recurrence, is associated with decreased acute toxicity and does not seem to affect breast appearance, late toxicity or patient-reported quality-of-life measures for selected women treated with breast conserving therapy. These are mostly women with node negative tumours smaller than 3 cm and negative pathological margins.

Fraction size in radiation treatment for breast conservation in early breast cancer

BACKGROUND

Shortening the duration of radiation therapy would benefit women with early breast cancer treated with breast conserving surgery. It may also improve access to radiation therapy by improving efficiency in radiation oncology departments globally. This can only happen if the shorter treatment is as effective and safe as conventional radiation therapy. This is an updated version of the original Cochrane Review published in Issue 3, 2008.

OBJECTIVES

To determine the effect of altered radiation fraction size on outcomes for women with early breast cancer who have undergone breast conserving surgery.

SEARCH STRATEGY

We searched the Cochrane Breast Cancer Group Specialised Register, MEDLINE, EMBASE and the WHO ICTRP search portal to June 2009, reference lists of articles and relevant conference proceedings. We applied no language constraints.

SELECTION CRITERIA

Randomised controlled trials of unconventional versus conventional fractionation in women with early breast cancer who had undergone breast conserving surgery.

DATA COLLECTION AND ANALYSIS

The authors performed data extraction independently, with disagreements resolved by discussion. We sought missing data from trial authors.

MAIN RESULTS

Four trials reported on 7095 women. The women were highly selected: tumours were node negative and 89.8% were smaller than 3 cm. Where the breast size was known, 87% had small or medium breasts. The studies were of low to medium quality. Unconventional fractionation (delivering radiation therapy in larger amounts each day but over fewer days than with conventional fractionation) did not affect: (1) local recurrence risk ratio (RR) 0.97 (95% CI 0.76 to 1.22, P = 0.78), (2) breast appearance RR 1.17 (95% CI 0.98 to 1.39, P = 0.09), (3) survival at five years RR 0.89 (95% CI 0.77 to 1.04, P = 0.16). Acute skin toxicity was decreased with unconventional fractionation: RR 0.21 (95% CI 0.07 to 0.64, P = 0.007).

AUTHORS' CONCLUSIONS

Two new studies have been published since the last version of the review, altering our conclusions. We have evidence from four low to medium quality randomised trials that using unconventional fractionation regimens (greater than 2 Gy per fraction) does not affect local recurrence, is associated with decreased acute toxicity and does not seem to affect breast appearance or late toxicity for selected women treated with breast conserving therapy. These are mostly women with node negative tumours smaller than 3 cm and negative pathological margins. Long-term follow up (> 5 years) is available for a small proportion of the patients randomised. Longer follow up is required for a more complete assessment of the effect of altered fractionation.

Fraction size in radiation treatment for breast conservation in early breast cancer

BACKGROUND

Shortening the duration of radiation therapy would benefit women with early breast cancer treated with breast conservation. It may also improve access to radiation therapy by improving efficiency in radiation oncology departments globally. This can only happen if the shorter treatment is as effective and safe as conventional radiation therapy.

OBJECTIVES

To assess the effects of altered fraction size on women with early breast cancer who have undergone breast conserving surgery.

SEARCH STRATEGY

We searched the Cochrane Breast Cancer Group Specialised Register (June 2006), MEDLINE (November 2006), EMBASE (November 2006), reference lists for articles, and relevant conference proceedings. No language constraints were applied.

SELECTION CRITERIA

Randomised controlled trials of unconventional versus conventional fractionation in women with early breast cancer who had undergone breast conserving surgery.

DATA COLLECTION AND ANALYSIS

Data extraction was performed independently by the authors with disagreements resolved by discussion. Missing data was sought by contacting the authors concerned.

MAIN RESULTS

Two trials were included and reported on 2644 women. The women were highly selected with node negative tumours smaller than 5 cm and negative pathological margins; 46% of the women had a cup separation size of less than 25 cm. The studies were of high quality. Data for local recurrence and breast appearance were not available in a form which could be combined. Unconventional fractionation (delivering radiation therapy in larger amounts each day but over fewer days than with conventional fractionation) did not appear to affect: (1) local-recurrence free survival (absolute difference 0.4%, 95% CI -1.5% to 2.4%), (2) breast appearance (risk ratio (RR) 1.01, 95% CI 0.88 to 1.17; P = 0.86), (3) survival at five years (RR 0.97, 95% CI 0.78 to 1.19; P = 0.75), (4) late skin toxicity at five years (RR 0.99, 95% CI 0.44 to 2.22; P = 0.98, or (5) late radiation toxicity in sub-cutaneous tissue (RR 1.0, 95% CI 0.78 to 1.28; P = 0.99).

AUTHORS' CONCLUSIONS

We have evidence from two high quality randomised trials that the use of unconventional fractionation regimes (greater than 2 Gy per fraction) does not affect breast appearance or toxicity and does not seem to affect local recurrence for selected women treated with breast conserving therapy. These are women with node negative tumours smaller than 5 cm and negative pathological margins. Two new trials have been published in March 2008. Their results are consistent with our findings. The results of these trials will be incorporated in the next update of this review.

Will we need lymph node dissection at all in the future?

Traditionally in the treatment of primary breast cancer, axillary lymph node dissection (ALND) plays an important role. However, a substantial and increasing percentage of patients appear to have no nodal involvement and have been subjected to ALND unnecessarily. The first reason to perform an ALND is axillary nodal staging. After reviewing the literature, it can be concluded that in clinically node-negative patients an adequately conducted lymphatic mapping by sentinel node procedure is equal to ALND for this purpose. The second reason to perform an ALND is to establish the extent of nodal involvement, which might have an impact on adjuvant treatment recommendations. However, there is no evidence available that patients with extensive nodal involvement (= 4 positive nodes) benefit more from adjuvant systemic treatment (either standard or high dose) in terms of reduction of odds of recurrence and mortality compared to patients with limited nodal involvement and optimally administered so-called standard adjuvant treatment. The third reason to perform an ALND is to ensure axillary tumor control. Reviewing the different treatment options, it can be concluded that in clinically node-negative patients axillary control after axillary radiotherapy appears to be similar to axillary control after ALND. In clinically overt axillary involvement, ALND (with or without adjuvant radiotherapy) may result in an improved regional control. In the near future, ALND will not be the standard of care but will be reserved for those patients with proven axillary lymph node involvement. In microscopic disease, radiotherapy may be an alternative with equal control and less morbidity.

Intensity-modulated radiation therapy: the inverse, the converse, and the perverse

Intensity-modulated radiation therapy (IMRT) is a refinement of current radiotherapy techniques rather than a major breakthrough. The term IMRT includes several different techniques that all share with classical arc therapy the principle of using multiple fields to reduce the dose to normal tissues, but integrating to a higher dose throughout the tumor volume itself. This paper reviews not only the putative upside but also the downside of the development of IMRT. Theoretical, practical, and cost considerations, both positive and negative, are discussed. There are several issues to be considered, but the most important perversely predict a significant increase in radiation-induced neoplasms, resulting not only from larger volumes of tissue exposed to more modest but still mutagenic doses, but also from a significant increase in total body dose from leakage, because the beam is typically on for a considerably longer period of time than is conventional. A plea is made for radiation oncologists to maintain a strong biologic and cellular orientation as oncology rapidly becomes more molecular in its orientation.

[Postmastectomy locoregional radiotherapy for breast cancer: literature review]

Postoperative radiotherapy is controversial after radical mastectomy. Recent clinical trials have shown an increase in survival with this irradiation and conclusions of previous meta-analyses should be reconsidered. The results of a large number of randomized clinical trials in which women received post-mastectomy radiotherapy or not have been reviewed. These trials showed a decrease in locoregional failure with the use of postoperative radiotherapy but survival advantages have not been clearly identified. A larger number of randomized clinical trials compared postoperative radiotherapy alone, chemotherapy alone and the association of the two treatments. They showed that chemotherapy was less active locally than radiotherapy and that radiotherapy and chemotherapy significantly increased both disease-free and overall survival rates in the groups which received postoperative radiotherapy. These favourable results were, however, obtained with optimal radiotherapy techniques and a relative sparing of lung tissue and cardiac muscle. Many retrospective clinical analyses concluded that results obtained in locoregional failure rate were poor and that these failures led to an increase in future risks. Both radiotherapy and systemic treatment should be delivered after mastectomy, reserved for patients with a high risk of locoregional relapses, particularly of nodes and/or tumors with a diameter > or = 5 cm. However, radiotherapy could produce secondary effects, and techniques of radiotherapy should be optimal.

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.

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.

Cardiac doses in post-operative breast irradiation

Data were collected on radiation doses given to the heart and coronary arteries during primary breast irradiation in order to analyze factors which might be important in the aetiology of subsequent cardiac-related disease. Twenty eight patients with breast cancer were studied. Fourteen patients treated from 1957 to 1984 were studied retrospectively (group 1), and 14 treated from 1988 to 1989 were studied prospectively (group 2). All patients had stage I or II disease at presentation, and were under 70 years of age. None had chemotherapy as a primary form of treatment. Patients were given a computed tomography scan of the chest, and three-dimensional reconstruction was made of the heart, lung and body contour. Original dose distributions were super-imposed on these outlines, and doses to the total cardiac volume and three main coronary arteries were estimated using an alpha/beta ratio of 4 Gy. Nine out of 14 patients in group 1 had a mastectomy followed mainly by orthovoltage radiation with similar techniques used up until 1984. Thirteen out of 14 patients in group 2 had conservative surgery followed by a modern two- or four-field megavoltage technique. We found that for patients with left-sided tumours (n = 20), the heart volume irradiated to a minimum extrapolated target dose of 5 Gy is significantly decreased for patients treated with a modern technique (group 2) when compared with those treated with earlier techniques (group 1).(ABSTRACT TRUNCATED AT 250 WORDS)

Late effects of radiotherapy in the treatment of breast cancer

Late effects after radiotherapy for breast cancer include radiation induced malignancy and changes in irradiated tissues leading to e.g. edema of the arm, decreased mobility of the shoulder joint, brachial plexus neuropathy, pulmonary fibrosis, telangiectasia or atrophic ulceration of the skin. While radiation-induced malignancy depends on the volume of tissue irradiated and the total dose, other late effects are also fractionation dependent. Several reports have shown increased rates of such late effects after changes of the fractionation schedule which should be isoeffective according to the mathematical models commonly used to predict early effects. Although knowledge of the relation between total dose, number of fractions and radiation effects in late responding tissues has increased, extrapolations from the models should be used cautiously. The dose-response curve seems to be steeper for late effects than for tumour control. The possibility of late effects should be included in the decision as to when and how to treat breast cancer with radiotherapy.

Prognostic factors associated with survival after breast cancer recurrence

Factors associated with disease-free interval after the primary treatment and survival after a recurrence of breast cancer were studied in 331 female breast cancer patients treated in 1976-1980. Within five years after the primary treatment, recurrence occurred in 131 patients. The observation time of these patients after recurrence was from few weeks to twelve years. Twenty-nine patients were alive at the end of the follow-up. The average disease-free time was 2 years. The clinical stage of the disease in this material was not significantly associated with the disease-free interval. The median survival time after recurrence was 2.7 years when only breast cancer related deaths were included. Survival was significantly better for patients with primarily stage I disease than for patients with primarily stage II-IV disease. The size of the primary tumour was not significantly associated with survival after recurrence. The patients with loco-regional recurrence survived almost significantly better than those with distant recurrence. The disease-free time correlated positively with survival after a recurrence. The present study confirms the view that breast cancer includes several subgroups with a different type of clinical course.

Postoperative radiotherapy and late mortality: evidence from the Cancer Research Campaign trial for early breast cancer

OBJECTIVE

To identify any excess mortality caused by adjuvant radiotherapy for early breast cancer.

DESIGN

Prospective randomised clinical trial. Two thousand subjects needed for study to have a 90% chance of detecting a difference in survival rate of 7% with 95% significance. Patients were followed up until June 1988, giving follow up of 158-216 months.

SETTING

A multicentre trial mainly drawing patients from centres in the United Kingdom.

PATIENTS

2800 Women presenting with clinical stage I or II carcinoma of the breast from June 1970 to April 1975.

INTERVENTIONS

One group of women (n = 1376) had simple mastectomy followed by immediate postoperative radiotherapy (1320 to 1510 rets). The remaining women (n = 1424) had simple mastectomy with subsequent careful observation of the axilla, radiotherapy being delayed until there was obvious progression or recurrence of disease locally.

END POINT

Increased mortality in patients treated with radiotherapy from causes other than breast cancer.

MEASUREMENTS AND MAIN RESULTS

Survival was measured from time of first treatment to death or last follow up. Deaths from any cause and from specified causes were counted as events. Comparison over the whole follow up showed a slight excess mortality in the group treated with radiotherapy (relative risk 1.04; 95% confidence interval 0.94 to 1.15). The relative risk of death from breast cancer was 0.97 (0.87 to 1.08) but that of death from other causes was 1.37 (1.09 to 1.72), the increase mainly being in women who had had tumours of the left breast (1.61 (1.17 to 2.24)) and had been treated with orthovoltage (1.85 (1.27 to 2.71)). Analysis of causes of death after five years showed a relative risk of 2.11 (1.25 to 3.59) for new malignancies and of 1.65 (1.05 to 2.58) for cardiac disease, the increase in cardiac mortality being most pronounced in patients who had had tumours of the left breast and whose treatment had included orthovoltage radiation (relative risk 2.67 (1.28 to 5.55)).

CONCLUSIONS

Adjuvant radiotherapy after simple mastectomy for early breast cancer produces a small excess late mortality from other cancers and cardiac disease. The risk has to be balanced against the higher risk of local recurrence when immediate postoperative radiotherapy is not given. The balance has to be assessed for each patient, and for many patients radiotherapy will still be desirable in the initial treatment of their early breast cancer.

Adjuvant radiotherapy in breast cancer. Consideration of cost-benefits in relation to the CRC (Cancer Research Campaign) (King's/Cambridge) trial

The Cancer Research Campaign (CRC) Trial demonstrates a decreased incidence of local recurrence for patients randomized to prophylactic radiotherapy following mastectomy. Irradiated patients alive after 5 years, however, have a small increased risk of dying from causes other than breast cancer. How to estimate the cost-benefit of such therapy is discussed.

The 10-year results of a prospective trial of post-operative radiotherapy delivered in 3 fractions per week versus 2 fractions per week in breast carcinoma

The 10-year results are presented of a prospective trial of 411 patients with breast carcinoma treated by mastectomy and post-operative radiotherapy given in either 2 or 3 fractions per week (i.e. a comparison of 6 fractions in 18 days with 12 fractions in 28 days). The early radiation effects on the normal tissues were similar and acceptable. The late skin changes in the chest wall (treated with 70 kV X rays) were progressive and by 10 years were slightly more marked with 6 fractions. Late subcutaneous fibrosis in the axilla (treated with cobalt-60 teletherapy), however, was much less in the 6-fraction group. Twelve fractions resulted in greater restriction of shoulder movement and an increased incidence of lymphoedema of the arm. Doses were selected on the basis of past clinical experience. The dose used to treat the axilla in 6 fractions was 35 Gy, 14.99% less than that predicted by NSD. The dose predicted by alpha:beta, using a value of 2 Gy for late reactions, is 38.14 Gy. Thus simple theory, which omits time, still predicts too high a dose for 6 fractions, although it is closer than NSD. In this trial, the 6-fraction technique showed an advantage over the 12-fraction technique. It was equally effective in controlling local recurrence and had fewer late sequelae. It was also convenient for patients and economic in the use of radiotherapy resources.