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ScienceWeek
MEDICINE: BREAST CANCER SCREENING IN UK VS. US
The following points are made by R. Smith-Bindman et al (J. Am. Med. Assoc. 2003 290:2129):
1) The provision of screening mammography differs greatly between the US and the UK. In the US, screening is provided in diverse settings, such as private practice, health maintenance organizations, and academic medical centers(1); whereas in the UK, a single organized screening program run by the National Health Service provides virtually all mammographic screening for women aged 50 years or older.(2-3) There are also differences between the ages of women screened; the recommended interval between mammographic examinations; the proportion of women recalled for additional imaging examinations, such as diagnostic mammography or ultrasound; and the methods used to further evaluate findings considered suspicious for cancer.(4,5) However, it is not clear if there are actual differences in the performance and outcomes of screening mammography between the two countries. Comparing the performance of screening mammography between the two countries may suggest methods to improve mammography practice.
2) The authors compared recall (the percentage of mammograms in which there is a recommendation for prompt additional testing, clinical evaluation, or percutaneous biopsy), surgical biopsy, and cancer detection rates for screening mammography among similarly aged women between the United States and the United Kingdom. The analysis included 5.5 million mammograms.
3) The authors report that the recall and negative open surgical biopsy rates associated with screening mammograms were twice as high in US settings than in the UK; however, cancer detection rates were similar in the two countries. In the UK, half as many women are recalled for diagnostic examinations and half as many women without breast cancer undergo open surgical biopsies as in the US. These results observed in large numbers of women are similar to recent findings from a series of 60 test cases evaluated by physicians in both countries in whom false-positive rates were higher among US physicians but cancer detection rates were not.
4) The authors conclude: "Recall and negative open surgical biopsy rates are twice as high in US settings than in the UK but cancer detection rates are similar. Efforts to improve US mammographic screening should target lowering the recall rate without reducing the cancer detection rate."
References (abridged):
1. Houn F, Brown M. Current practice of screening mammography in the United States: data from the National Survey of Mammography Facilities. Radiology. 1994;190:209-215
2. Blanks R, Moss S, Patnick J. Results from the United Kingdom NHS breast screening program 1994-1999. J Med Screen. 2000;7:195-198
3. UK National Health Service Breast Screening Web site. The NHS Breast Screening Program. Available at: http://www.cancerscreening.nhs.uk/breastscreen. Accessibility verified September 10, 2003
4. Brown M, Houn F, Sickles E, Kessler L. Screening mammography in community practice: positive predictive value of abnormal findings and yield of follow-up diagnostic procedures. AJR Am J Roentgenol. 1995;165:1373-1377
5. Blanks R, Bennett R, Wallis M, Moss S. Does individual program size affect screening performance? results from the United Kingdom NHS breast screening program. J Med Screen. 2002;9:11-14
J. Am. Med. Assoc. http://www.jama.com
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BREAST CANCER: ON RADICAL MASTECTOMY VS. CONSERVATIVE SURGERY
The following points are made by U. Veronesi et al (New Engl. J. Med. 2002 347:1227):
1) The radical mastectomy introduced by Halsted(1) was the treatment of choice for breast cancer of any size or type, regardless of the patient's age, for 80 years. Apart from a few modifications, such as enlarging the extent of the dissection to include the internal mammary nodes or reducing it to spare the pectoralis muscles, the Halsted mastectomy was performed as originally described throughout this period. The possibility of attempting a surgical procedure that would conserve the breast was not widely considered during those years.(2,3)
2) In 1969, a randomized study to compare radical mastectomy with breast-conserving surgery, which was termed "quadrantectomy", was approved by the World Health Organization Committee of Investigators for Evaluation of Methods of Diagnosis and Treatment of Breast Cancer.(4) The recruitment of patients began at the Milan Cancer Institute in 1973, after the new procedure was standardized, and preliminary data showing that survival rates were equal after radical and breast-conserving surgery were published in 1977(5) and 1981.
3) The main criticism of the data was that they were too preliminary; patients with small breast cancers must be followed for a very long time, even decades, to ensure that the evaluation of the efficacy of any new treatment is accurate. The authors carefully monitored the 701 women in the trial for up to 29 years, and they now report the results.
4) Thirty women in the group that underwent breast-conserving therapy had a recurrence of tumor in the same breast, whereas eight women in the radical-mastectomy group had local recurrences (P < 0.001). The crude cumulative incidence of these events was 8.8 percent and 2.3 percent, respectively, after 20 years. In contrast, there was no significant difference between the two groups in the rates of contralateral-breast carcinomas, distant metastases, or second primary cancers. After a median follow-up of 20 years, the rate of death from all causes was 41.7 percent in the group that underwent breast-conserving surgery and 41.2 percent in the radical-mastectomy group (P=1.0). The respective rates of death from breast cancer were 26.1 percent and 24.3 percent (P=0.8).
5) The authors conclude: The long-term survival rate among women who undergo breast-conserving surgery is the same as that among women who undergo radical mastectomy. Breast-conserving surgery is therefore the treatment of choice for women with relatively small breast cancers.
References (abridged):
1. Halsted WS. A clinical and histological study of certain adenocarcinomata of the breast: and a brief consideration of the supraclavicular operation and of the results of operations for cancer of the breast from 1889 to 1898 at the Johns Hopkins Hospital. Ann Surg 1898;28:557-576.
2. Hirsch J. Radiumchirurgie des Brustkrebses. Dtsch Med Wochenschr 1927;53:1419-1421.
3. Keynes G. Conservative treatment of cancer of the breast. BMJ 1937;2:643-647.
4. Meeting of investigators for evaluation of methods of diagnosis and treatment of breast cancer: final report. Geneva: World Health Organization, December 1969.
5. Veronesi U, Banfi A, Saccozzi R, et al. Conservative treatment of breast cancer: a trial in progress at the Cancer Institute in Milan. Cancer 1977;39:Suppl:2822-2826.
New Engl. J. Med. http://www.nejm.org
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CONSERVATIVE TREATMENT OF BREAST CANCER. A TRIAL IN PROGRESS AT THE CANCER INSTITUTE OF MILAN.
The following points are made by U. Veronesi et al (Cancer 1977 39(6 Suppl):2822):
1) The authors report a clinical trial on conservative surgery in progress at the National Cancer Institute of Milan, Italy. The randomized clinical trial compares radical mastectomy with a more conservative procedure consisting of mammary resection plus axillary dissection plus radiotherapy. The resection comprises an entire quadrant of the breast together with the overlying skin and the corresponding portion of the fascial sheet of the pectoralis major. The axillary dissection is performed in continuity with the resected breast quadrant except in cases with tumors of lower inner quadrants, who need two separate incisions. After surgery the patients receive 6000 rads to the residual breast tissue over five to six weeks, starting 15 days after operation.
2) The cosmetic results are satisfactory in approximately 70% of cases. The trial is limited to cases with tumors less than 2 cm and no palpable axillary nodes (T1N0M0). Patients with histologically positive lymph nodes (N+) are submitted to adjuvant chemotherapy with CMF for one year. From September 1973, to October 1976, 331 cases entered the trial. One hundred sixty were treated with radical mastectomy and 164 with the conservative procedure. Axillary metastases were found in 23% of the radical and in 29% of the conservative surgery group. Four local-regional recurrences have occurred till now, two in each group. Five cases in the radical mastectomy group and one in the conservative group had distant metastases. The clinical trial will collect some 500 cases by the end of 1977 and significant preliminary results are expected to be available from 1978. .
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COMPARING RADICAL MASTECTOMY WITH QUADRANTECTOMY, AXILLARY DISSECTION, AND RADIOTHERAPY IN PATIENTS WITH SMALL CANCERS OF THE BREAST.
The following points are made by U Veronesi, et al: (New Engl. J. Med. 1981 305:6):
1) The authors report that from 1973 to 1980 they carried out a controlled study at the National Cancer Institute in Milan to consider the value of a conservative procedure in patients with breast cancer of small size. The authors randomized 701 patients with breast cancer measuring less than 2 cm in diameter and with no palpable axillary lymph nodes to Halsted radical mastectomy or to "quadrantectomy" with axillary dissection and radiotherapy to the ipsilateral residual breast tissue. The authors treated 349 patients with Halsted mastectomy and 352 with quadrantectomy. The two groups were comparable in age distribution, size and site of primary tumor, menopausal status, and frequency of axillary metastases. There were three local recurrences in the Halsted group and one in the quadrantectomy group. Actuarial curves showed no difference between the two groups in disease-free or overall survival.
2) From these results, mastectomy appears to involve unnecessary mutilation in patients with breast cancer of less than 2 cm and no palpable axillary nodes.
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CUMULATIVE CAUSE-SPECIFIC MORTALITY FOR CANCER PATIENTS IN THE PRESENCE OF OTHER CAUSES: A CRUDE ANALOGUE OF RELATIVE SURVIVAL.
The following points are made by K.A. Cronin and E.J. Feuer (Stat Med 2000 19:1729):
1) A common population-based cancer progress measure for net survival (survival in the absence of other causes) of cancer patients is relative survival. Relative survival is defined as the ratio of a population of observed survivors in a cohort of cancer patients to the proportion of expected survivors in a comparable set of cancer-free individuals in the general public, thus giving a measure of excess mortality due to cancer.
2) Relative survival was originally designed to address the question of whether or not there is evidence that patients have been cured. It has proven to be a useful survival measure in several areas, including the evaluation of cancer control efforts and the application of cure models. However, it is not representative of the actual survival patterns observed in a cohort of cancer patients.
3) The authors suggest a measure for cumulative crude (in the presence of other causes) cause-specific probability of death for a population diagnosed with cancer. The measure does not use cause of death information, which can be unreliable for population cancer registries. Point estimates and variances are derived for crude cause-specific probability of death using relative survival instead of cause of death information. Examples are given for men diagnosed with localized prostate cancer over the age of 70 and women diagnosed with regional breast cancer using Surveillance, Epidemiology and End Results (SEER) Program data.
4) The examples emphasize the differences in crude and net mortality measures and suggest areas where a crude measure is more informative. Estimates of this type are especially important for older patients as new screening modalities detect cancers earlier and choice of treatment or even "watchful waiting" become viable options.
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