Japanese Journal of Clinical Oncology Advance Access originally published online on October 2, 2007
Japanese Journal of Clinical Oncology 2007 37(10):737-743; doi:10.1093/jjco/hym096
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© 2007 Foundation for Promotion of Cancer Research
Patterns of Care Study of Breast-conserving Therapy in Japan: Comparison of the Treatment Process between 1995–1997 and 1999–2001 Surveys
1 Japanese PCS Working Subgroup of Breast Cancer
2 Department of Radiation Oncology and Image-applied Therapy, Graduate School of Medicine, Kyoto University, Kyoto
3 Department of Radiology, Shinshu University, School of Medicine, Matsumoto, Nagano
4 Department of Medical Physics and Engineering, Osaka University Graduate School of Medicine, Suita, Osaka
5 Department of Radiation Oncology Osaka University Graduate School of Medicine, Suita, Osaka, Japan
For reprints and all correspondence: Chikako Yamauchi, Department of Radiation Oncology and Image-applied Therapy Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan; E-mail: chikay{at}kuhp.kyoto-u.ac.jp
Received January 26, 2007; accepted June 8, 2007
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Abstract |
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 TOP Abstract INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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Background: The Japan Patterns of Care Study (JPCS) conducted two national surveys to identify changes associated with the treatment process of care for patients undergoing breast-conserving therapy (BCT). Between the two national surveys, the Japanese Breast Cancer Society published its treatment guideline for BCT.
Method: The first survey collected data on 865 patients treated between 1995 and 1997 (JPCS-1), and the second on 746 patients treated between1999 and 2001 (JPCS-2) by extramural audits.
Results: There was a shift to an older age distribution in JPCS-2 compared with JPCS-1. In JPCS-2, the average patient age was 53.9 compared with 51.5 in JPCS-1 (P < 0.001). There was a reduction in the extent of breast surgery and the proportion of the patients who received quadrantectomy was 57.0% in JPCS-1 and 30.3% in JPCS-2 (P < 0.001). In JPCS-2, a cast or shell for immobilization was used at a significantly higher rate of 52.9% compared with 32.6% for JPCS-1 (P < 0.001). The rate of boost irradiation was increased in JPCS-2, especially for patients with a positive surgical margin; it was significantly increased to 83.5% in JPCS-2 compared with 53.9% in JPCS-1 (P < 0.001).
Conclusions: The second survey revealed a rapid change in the trend of the treatment of BCT in Japan and represented high compliance of the treatment guideline for BCT published by the Japanese Breast Cancer Society (JBCS) in 1999.
Key Words: patterns of care study • breast cancer • breast conserving-therapy • radiation therapy
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INTRODUCTION |
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TOPAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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Breast-conserving therapy (BCT) was incorporated into practice in the mid 1980s in Japan. Since then, the number of patients with breast cancer undergoing BCT has been rapidly increasing, and BCT is now the treatment of choice for early breast cancers in Japan. According to a national survey by the Japanese Breast Cancer Society (JBCS) in the year 2003 (1), 48.4% of patients received BCT. The Patterns of Care Study (USPCS) by the American College of Radiology has made significant contributions to improvements in care of patients with breast cancer in the United States (2,3). The Japan Patterns of Care Study Group (JPCS) started its national survey for breast cancer in 1998. The first survey (JPCS-1) collected data on 865 patients who underwent BCT between 1995 and 1997, and revealed considerable variation and some inappropriate implementation of the BCT treatment process in Japan at that time (4). On the other hand, the Japanese Breast Cancer Society published its treatment guideline for BCT in 1999. The purpose of this study is to compare the results of the two national surveys and to evaluate the impact of the JBCS guideline at the same time since the cases of JPCS-2 were treated after the publication of the guidelines.
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MATERIALS AND METHODS |
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TOPAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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The JPCS conducted two national surveys. From September 1998 to December 1999, JPCS-1 collected the data on patients treated between1995 and 1997, and from July 2002 to June 2004, JPCS-2 collected data on patients treated between 1999 and 2001. The institutions and patients were selected by two-stage cluster sampling (5). For JPCS-1, 556 institutions nationwide were stratified into four classifications based on the Japanese facility master list in 1995, and for JPCS-2 640 institutions were stratified into four classifications in 2001. The JPCS-1 randomly selected 72 institutions and collected data on 865 BCT cases which were randomly sampled from lists of eligible patients that were supplied by the institutions. The JPCS-2 also selected 76 institutions and collected data on 746 cases. (Table 1). The data was collected by extramural audits of institutions and the auditors were member physicians of the Japanese PCS Working Group. For JPCS-1, we used a data format that was developed on the basis on the USPCS data format and a computer file in FileMaker Pro® version 4.0 database (FileMaker Inc., Santa Clara, CA, USA). For JPCS-2, we developed a new data format on the Access® 2000 database (Microsoft) according to the revised best current management drafted by JPCS Working Subgroup of Breast Cancer. They consist of 316 and 362 items on the BCT process, respectively. The data was collected from all available resources at the location, not only from charts of the radiation oncology department. The eligibility criteria for these analyses were as follows: (1) female; (2) absence of gross multiple tumors; (3) absence of diffuse micro-calcification on pre-treatment mammography; (4) absence of distant metastases; (5) no bilateral lesions; (6) no prior or concurrent malignancies; (7) no prior history of the irradiation of the breast; and (8) no collagen vascular disease other than rheumatoid arthritis. The extent of surgery, prescription and technique of radiation therapy, and the regimen of systemic chemo-endocrine therapy were compared between the two surveys. In the tables below, ‘unknown’ indicates that the item in the format was filled with data labeled as ‘unknown’, whereas ‘missing’ means that the item in the format was left empty. We combined ‘unknown’ and ‘missing’ in the tables because their meanings were the same in most cases: no valid data was found in the given resources. ‘Unknown/missing’ data for categorical data were included in the ratio calculation, whereas the data for the continuous variables was excluded from the ratio calculation, as seen in a corresponding report from the USPCS (6). Paired and unpaired t-tests and chi-square tests were used for statistical analyses where appropriate. A P value of less than 0.05 was regarded as significant.
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RESULTS |
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Patient Characteristics
The patient characteristics are shown in Table 2. Compared with JPCS-1, patients in JPCS-2 had an older age distribution. In JPCS-2, the average patient age was significantly increased from 51.5 in JPCS-1 to 53.9 (P < 0.001), and 60% of the patients were
50 years of age, compared with 47% in JPCS-1 (P < 0.001).
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Evaluation and Staging
The evaluation and staging of the tumors are shown in Table 3. In JPCS-1, mammography was performed on 79.4% of the patients during their evaluation compared with 65.5% in JPCS-1, although the number of missing/unknown is large. In JPCS-1, the proportions of patients with tumors of <2 and 2–5 cm were 70.3 and 28.9%, respectively, although it was frequently unknown. In JPCS-2, 52.5% of the patients had tumors of <2 cm and 46.3% had 2–5 cm tumors.
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Surgical Procedures
The results of the surgical procedures are shown in Table 4. There was a reduction in the extent of breast surgery, and the ratio of the patients who received quadrantectomy was 57.0% in JPCS-1 and 30.3% in JPCS-2 (P < 0.001). Axillary LN dissection was performed on 94.3% of the patients in JPCS-1 and 90.9% in JPCS-2 (P = 0.008). On the other hand, 12.2% of the patients underwent sentinel lymph node biopsy (SLNB) in JPCS-2, although the data about SLNB was not collected in JPCS-1.
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Histopathological Assessment
The results of the histopathological assessment are shown in Table 5. In JPCS-2, 79.6% of the pathology reports were shown on the charts and the rate was significantly higher than in the prior study (P < 0.001). The final microscopic margin was stated for 96.2% of the patients in JPCS-2 and for 88.8% in JPCS1 (P < 0.001). The surgical margin was defined as ‘positive margin’ in this study, when there were malignant cells at the surgical margin. The final microscopic margin was positive in 7.5 and 13.0% of the patients in JPCS-1 and JPCS-2, respectively. In JPCS-1, estrogen receptor evaluation was performed for 54.9% of the patients, and in JPCS-2 it increased to 78.0% (P < 0.001). In JPCS-1, 49.6% of the patients underwent progesterone receptor evaluation, and in JPCS-2 this increased to 75.0% (P < 0.001). In JPCS-1 and JPCS-2, axillary lymph node was pathologically positive in 21.9 and 26.0% of the patients, respectively (P = 0.078).
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Systemic Therapy
Tamoxifen was given to 60.4% of the patients in JPCS-1 and 68.8% in JPCS-2 (P < 0.001). The administration of tamoxifen according to the hormone receptor is shown in Table 6. In JPCS-1 and JPCS-2, tamoxifen was administered to 72.5 and 85.3% of the receptor-positive patients, respectively (P < 0.001). Also, tamoxifen was given to 52.3% of the receptor-negative patients in JPCS-1, and 39.5% in JPCS-2 (P = 0.03). Chemotherapy, defined as all kinds of chemotherapy including single-agent oral administration of 5-FU or its derivatives, was administered to 38.7% of the patients in JPCS-1 and 35.0% in JPCS-2 (P = 0.001). The administration of chemotherapy according to pathological lymph nodes is shown in Table 7. For 64.4 and 73.9% of the patients who had pathologically positive lymph nodes, respectively, chemotherapy was administered in JPCS-1 and JPCS-2 (P = 0.06). In addition, the use of chemotherapy that incorporated at least one out of doxorubicin, cyclophosphamide, methotrexate, mitomycin, mitoxantrone, paclitaxel, vinblastine, and vincristine increased significantly during the two survey periods, with 36.9% in JPCS-1 and 52.3% in JPCS-2 (P = 0.02)
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Radiation Therapy
Table 8 presents details of the radiation planning. In JPCS-2, a cast or shell for immobilization was used on only 52.9% of the patients, although the rate was significantly higher than in JPCS-1 (P < 0.001). The clinical set-up of the radiation treatment was planned without the aid of computed tomography (CT) or X-ray simulation for 5.8% of JPCS-2 cases compared with 10.1% in JPCS-1 (P = 0.002). On the other hand, CT simulation was used for 26.7% of JPCS-2 cases compared with 22.2% of JPCS-1 cases (P = 0.037). Whole breast irradiation was performed on almost all cases in both surveys (Table 9). Additionally, 49.7% of JPCS-2 cases also had the regional nodes treated, compared with 53.7% in JPCS-1. Breast irradiation was given predominantly with photons of 6 MV (91.3%) in JPCS-2 compared with JPCS-1 (73.3%; P < 0.001). Photons of 10 MV without bolus, which is inappropriate for small breasts, was used on up to 4.4% of the patients in JPCS-1 and 2.0% in JPCS-2. Matching of the dorsal margin of tangential fields was not performed for 17.3% of JPCS 1 cases and 14.4% of JPCS-2 cases (P = 0.069). The median total dose to the whole breast was 50 Gy in JPCS-1 and JPCS-2. Boost irradiation was administered to 16.9% of JPCS-1 patients and 27.4% of JPCS-2 patients (P < 0.001) (Table 10). In particular, for the patients with a positive surgical margin, the rate of boost irradiation was significantly increased to 83.5% in JPCS-2 compared with 53.9% in JPCS-1 (P < 0.001). The median boost dose was 10 Gy in both surveys.
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DISCUSSION |
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TOPAbstractINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONReferences |
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The Patterns of Care Study was originally developed in the United States and assesses the evaluation and treatment patterns of malignancies. The Japan Patterns of Care Study Group started its national survey in 1998 and carried out two national surveys. This report documents the evaluation process and management of BCT in Japan.
BCT for breast cancer was introduced in Japan in the late 1980s, although it was started in the early 1970s in North America and Europe. At that time, it tended toward attaching great importance to surgery and the extent of breast surgery was large, although the feasibility of BCT had been recognized in the Western countries. Moreover, breast-conserving surgery (BCS) without radiation was commonly performed in Japan. In the 1990s, BCS spread rapidly and in 2003 the rate exceeded that of mastectomy in Japan. It was demonstrated that breast radiation significantly reduces ipsilateral breast recurrence in several important reports, and this treatment has been spreading in Japan. As a result, the rate of BCT without radiation has been decreasing and was 22.2% in 2003, although it might not be high enough (1). In PCS, the data from only patients who underwent radiation was collected but we could catch the general current of the process in BCT.
As regards patient characteristics, in JPCS-2 there was an older age distribution compared with JPCS-1. The shift could be a reflection of greater acceptance of conservative surgery and irradiation for older women as well as younger women. As regards evaluation, the rate of mentioning menstrual status rather than change of the status should be noted. Menstrual status is one of the most important factors in making the decision to use systemic therapy, but the data was unknown or missing in 17.8% of JPCS-1 patients. The rate was significantly decreased to 10.2% in JPCS-2, although it is still high.
The extent of surgical resection was significantly diminished and the rate of positive or close surgical margin was increased correlatively. This might be a result of reliance on breast irradiation. The rate of axillary dissection decreased in the second survey compared with the previous survey, which is consistent with the use of sentinel node biopsy (SNB). In 1996, sentinel lymph node (SLN) biopsy was introduced in Japan and has rapidly spread in Japan as in Western countries. It was reported that 21.5% of breast cancer patients in Japan underwent SLN biopsy in 2003 (7). However, in this study 61.8% of patients who underwent SNB also underwent axillary dissection.
The timing of the second survey was probably during the validation process for SNB by institutional surgeons. The use of SNB without axillary dissection will increase because current studies (8) have suggested that axillary dissection is not necessary for patients with negative sentinel nodes. Over the last few decades, there has been a major shift towards less invasive local treatment of breast cancer and BCT has largely replaced mastectomy as the surgical treatment of choice for early-stage breast cancer. In this trend, SLN biopsy will be accepted as an effective method of assessing axillary nodal status and avoiding unnecessary axillary dissection in patients with node-negative breast cancer. We therefore need to continue monitoring SNB.
The administration of tamoxifen was previously independent of the hormone receptor status, but was individualized according to the receptor status in the second survey. The trend was more significant in A facilities than in B facilities. Chemotherapy was given to more patients in the present study than in the previous one. However, the oral administration of 5-FU or its derivatives, which has been commonly used in Japan, was still carried out for 43.1% of the patients, and chemotherapy such as CMF or regimens including anthrathycline was uncommon. In Japan, medical oncology has not been established as a profession, and surgeons decide regimens under the present conditions. However, surgeons have been adopting the guidelines for Western countries to decide the chemotherapy regimens. Therefore, the rate of standard regimens will probably increase in the near future.
CT-based planning of irradiation to the conserved breast has been common compared with that in the United States (3). CT scans were used to generate isodose curves in 60.0% of JPCS-1 and 62.9% of JPCS-2 cases, and the rate was much higher than in the United States (22.9%). CT-based planning enables the decision to be made of individualized beam arrangements to adjust for variation in body habitus. Thereby, it can improve dose homogeneity throughout the target volume and generates dose–volume histograms of critical organs.
On the other hand, planning without the aid of CT or X-ray simulation was not unusual in JPCS-1. The present survey showed an increase in the use of CT-based or X-ray simulation. Regarding parameters for treatment planning such as a fixation system, matching of the dorsal margin of tangential fields or beam modifiers, suboptimal radiation therapy was performed on some patients in JPCS-1. Although it has been improved to some degree, there is space for improvement in some aspects of JPCS-2.
As expected, most patients in JPCS-2 underwent whole breast irradiation. The use of boost irradiation was significantly increased in the present study, especially for patients with a positive surgical margin. The guidelines for BCT published by the JBCS recommend that boost irradiation to the tumor bed should be performed for patients with a positive or close surgical margin. Following these guidelines might result in an increase in the use of boost irradiation. Boost irradiation tends to be common even for patients with a negative surgical margin in Western countries, since usefulness of boost irradiation has been shown in two randomized trials (9,10). In the United States PCS, 88.7% of patients who underwent BCT received boost irradiation whether margin status was positive or not. However, it has not been accepted yet in Japan and this may have be a result of differences in the policies of margin assessment.
The current study revealed high levels of compliance with guidelines; however much more improvement is required in some points of radiation therapy. For example, a cast or shell for immobilization was used in only 52.9% of the patients in JPCS-2, although the rate was significantly higher than in JPCS-1. Regarding simulation, the clinical set-up of the radiation treatment was planned without the aid of CT or X-ray simulation for 5.8% of JPCS-2 cases, although the rate was decreased compared with JPCS-1.
In conclusion, the second survey revealed a rapid change in the trend of BCT treatment process in Japan. Although it also showed high compliance with the guidelines, there is room for improvement in the treatment process of BCT.
Conflict of interest statement
None declared.
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References |
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