|
MRI's high false positive rate has little impact on women's choice of preventive mastectomy
March 26, 2008Magnetic resonance imaging (MRI) falsely detects breast cancer in five out of every six positive scans according to new research into the use of MRI for women with a high, inherited risk of developing the disease. However, this high rate of false positives does not have a major impact on a woman's decision whether or not to have a prophylactic mastectomy.
The study, published today (Wednesday 26 March) in the April issue of the cancer journal, Annals of Oncology [1], also showed that MRI was very good at detecting genuine cases of invasive cancers and ductal carcinoma in situ (DCIS), a localised pre-cancer that can develop into invasive breast cancer, although the authors said that improvements in detection were still necessary.
The researchers from the Hereditary Cancer Clinic at Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands, followed 196 women with a BRCA1 or BRCA2 mutation, aged between 21 and 68 for an average of two years (a range of between one and nine years). Once the women had discovered that they carried a BRCA mutation (which gives a lifetime risk of breast cancer of up to 85 per cent and for ovarian cancer of up to 60 per cent) they made six-monthly visits to hospital to be examined by an experienced medical specialist and to have a mammography and, whenever possible, MRI. During their first surveillance visit, the researchers recorded whether the women had a preference for ongoing surveillance, or prophylactic mastectomy and/or a prophylactic salpingo-oophorectomy (removal of fallopian tubes and ovaries).
During the period of the study, which ran from 1999 to 2005, 41 per cent (81 of 196) of the women had at least one positive MRI or mammogram; breast cancer was detected in 17 women (11 from scanning, four during prophylactic mastectomy and two during the interval between surveillance visits). The researchers found that the sensitivity of mammography (the proportion of true positives) was 41 per cent, for MRI it was 60 per cent and for the two combined it was 71 per cent. The specificity of the techniques (proportion of true negatives) was 93 per cent for mammography and 90 per cent for MRI or a combination of the two.
The lead author of the study, Dr Nicoline Hoogerbrugge, associate professor and head of the Hereditary Cancer Clinic, said: "When we looked at the positive MRI results, we found that 83 per cent of them could not be confirmed histologically and were, therefore, false positives: five out of every six positive MRI scans."
The researchers also found that approximately six per cent of the BRCA mutation carriers who had normal findings from their clinical surveillance, mammograms and MRIs, and who underwent an intended prophylactic mastectomy, had an unsuspected malignancy. One was only four millimetres in size and it is known that MRI and mammograms have difficulty detecting lesions this small, but three were DCIS between six and 15mm. "This indicates that further improvement of early breast cancer detection is still necessary," said Dr Hoogerbrugge.
When interviewed during their first surveillance visit, 58 women (30 per cent) expressed a preference for a prophylactic mastectomy. Three had no preference, and the rest preferred to have ongoing surveillance. After some of these women had a positive scan, mastectomy was carried out in 90 per cent of those women who had expressed a preference for it, and in only 31 per cent of those who had preferred surveillance.
Dr Hoogerbrugge said: "During the first two years after the establishment of a BRCA mutation, four out of every ten female carriers were confronted with an abnormal MRI or mammography result, but this had a limited impact on their choice for prophylactic mastectomy. The final decision to actually undergo prophylactic mastectomy appeared to be determined more frequently by a woman's prior preference than by a positive scan. Significantly more women with a prior preference for prophylactic mastectomy opted for it after a positive scan than did women without such prior intention. We found that women with a mother with breast cancer were more likely to have a preference for mastectomy."
She said personal beliefs and the psychological impact of women's family medical histories seemed to be of major importance in women's decision-making process. "There are very few data available about how women decide upon prophylactic mastectomy. Both genetic counselling and breast cancer surveillance are events in the entire process of decision-making, but appear to have a limited impact.
"However, the fact that a false positive MRI result has little impact on a woman's choice of prophylactic mastectomy may indicate that she has made a well-balanced decision on this subject."
The researchers say that while the pros and cons of prophylactic mastectomy for BRCA mutation carriers remain controversial, with the effects on length and quality of life largely unknown, physicians should give detailed and unbiased information on the different treatments available and the breast cancer risk, including the number of malignancies that are not identified during breast cancer surveillance.
Dr Hoogerbrugge said: "It is important to give BRCA mutation carriers correct risk information for the decision process, because preventive surgery is irreversible."
She concluded: "This study has made me realise that for women at high hereditary risk of breast cancer, accurate detection techniques are of the utmost importance, even at the cost of a high false positive rate because most women can cope with a false positive MRI result."
###
Notes:
[1] The impact of a false-positive MRI on the choice for mastectomy in BRCA mutation carriers is limited. Annals of Oncology. doi:10.1093/annonc/mdm537. Ann Oncol 2008; 19: 655-659.
European Society for Medical Oncology
During the period of the study, which ran from 1999 to 2005, 41 per cent (81 of 196) of the women had at least one positive MRI or mammogram; breast cancer was detected in 17 women (11 from scanning, four during prophylactic mastectomy and two during the interval between surveillance visits). The researchers found that the sensitivity of mammography (the proportion of true positives) was 41 per cent, for MRI it was 60 per cent and for the two combined it was 71 per cent. The specificity of the techniques (proportion of true negatives) was 93 per cent for mammography and 90 per cent for MRI or a combination of the two.
The lead author of the study, Dr Nicoline Hoogerbrugge, associate professor and head of the Hereditary Cancer Clinic, said: "When we looked at the positive MRI results, we found that 83 per cent of them could not be confirmed histologically and were, therefore, false positives: five out of every six positive MRI scans."
The researchers also found that approximately six per cent of the BRCA mutation carriers who had normal findings from their clinical surveillance, mammograms and MRIs, and who underwent an intended prophylactic mastectomy, had an unsuspected malignancy. One was only four millimetres in size and it is known that MRI and mammograms have difficulty detecting lesions this small, but three were DCIS between six and 15mm. "This indicates that further improvement of early breast cancer detection is still necessary," said Dr Hoogerbrugge.
When interviewed during their first surveillance visit, 58 women (30 per cent) expressed a preference for a prophylactic mastectomy. Three had no preference, and the rest preferred to have ongoing surveillance. After some of these women had a positive scan, mastectomy was carried out in 90 per cent of those women who had expressed a preference for it, and in only 31 per cent of those who had preferred surveillance.
Dr Hoogerbrugge said: "During the first two years after the establishment of a BRCA mutation, four out of every ten female carriers were confronted with an abnormal MRI or mammography result, but this had a limited impact on their choice for prophylactic mastectomy. The final decision to actually undergo prophylactic mastectomy appeared to be determined more frequently by a woman's prior preference than by a positive scan. Significantly more women with a prior preference for prophylactic mastectomy opted for it after a positive scan than did women without such prior intention. We found that women with a mother with breast cancer were more likely to have a preference for mastectomy."
She said personal beliefs and the psychological impact of women's family medical histories seemed to be of major importance in women's decision-making process. "There are very few data available about how women decide upon prophylactic mastectomy. Both genetic counselling and breast cancer surveillance are events in the entire process of decision-making, but appear to have a limited impact.
"However, the fact that a false positive MRI result has little impact on a woman's choice of prophylactic mastectomy may indicate that she has made a well-balanced decision on this subject."
The researchers say that while the pros and cons of prophylactic mastectomy for BRCA mutation carriers remain controversial, with the effects on length and quality of life largely unknown, physicians should give detailed and unbiased information on the different treatments available and the breast cancer risk, including the number of malignancies that are not identified during breast cancer surveillance.
Dr Hoogerbrugge said: "It is important to give BRCA mutation carriers correct risk information for the decision process, because preventive surgery is irreversible."
She concluded: "This study has made me realise that for women at high hereditary risk of breast cancer, accurate detection techniques are of the utmost importance, even at the cost of a high false positive rate because most women can cope with a false positive MRI result."
###
Notes:
[1] The impact of a false-positive MRI on the choice for mastectomy in BRCA mutation carriers is limited. Annals of Oncology. doi:10.1093/annonc/mdm537. Ann Oncol 2008; 19: 655-659.
European Society for Medical Oncology
Prophylactic Mastectomy News and Current Prophylactic Mastectomy Events RSS98 percent of elective mastectomy patients would have reconstruction again, says ASPS study
Women who have breast reconstruction after an elective mastectomy are satisfied with their decision, have low complication rates and 98 percent would do it again.
Second breast cancer may be greater than thought for high-risk women without BRCA mutations
A preliminary analysis of ongoing research suggests that high-risk women with breast cancer who do not have a BRCA1/2 mutation may face a greater chance for developing a second breast cancer than previously thought. With the increased risk of cancer in these women, should sentinel node biopsy be considered at the time of prophylactic mastectomy, and how can women best be counseled after these findings?
Hereditary breast cancer -- a high cost to patient and health care provider alike
Some women who carry the BRCA gene mutation, which predisposes to breast cancer, may choose to have a prophylactic mastectomy rather than undertake lifetime surveillance, a Dutch scientist will tell the 6th European Breast Cancer Conference (EBCC-6) today (Wednesday 16 April).
Benefit of cancer prevention surgery differs between women with BRCA1 and BRCA2 mutations
The surgical removal of the ovaries has been widely adopted as a cancer-risk-reducing strategy for women with either BRCA1 or BRCA2 mutations.
More Women Are Choosing Double Mastectomy Even When Breast Cancer Is Confined to a Single Breast
Researchers are reporting a 150 percent increase between 1998 and 2003 in American women opting to have both breasts removed when cancer has been found in only one breast-a procedure called contralateral prophylactic mastectomy (CPM).
Magnetic resonance imaging improves breast cancer diagnosis
Women who have been diagnosed with breast cancer in one breast have a higher risk of contracting the disease in their opposite breast as well. A thorough examination of the opposite breast using mammography and ultrasound is therefore common practice.
Use of breast MRI can be cost-effective for some women at high-risk of breast cancer
A computer model simulation suggests that adding breast MRI screening may be cost-effective for women of certain ages who carry BRCA1 and BRCA2 gene mutations.
Center calls for stronger federal regulation of genetic testing
The Genetics and Public Policy Center this week called on Mark McClellan, Administrator of the Centers for Medicare and Medicaid Services (CMS), to end years of delay in assuring the safety and accuracy of genetic testing by issuing a proposed rule to create a genetic testing specialty under the Clinical Laboratory Improvement Amendments (CLIA) of 1988.
Mayo Clinic measures psychological and social impacts of contralateral prophylactic mastectomies
Mayo Clinic researchers report that most women who have a contralateral (opposite to cancerous breast) prophylactic mastectomy (CPM) are satisfied and would elect this procedure again. Satisfaction with CPM was studied an average of 10 years after the procedure was done.
Women face high risk of developing breast cancer following radiotherapy for Hodgkin’s Disease
Women who have received radiotherapy for Hodgkin’s Disease have a three times higher relative risk of developing breast cancer than women from the general population, Professor Dietlind Wahner-Roedler told the 3rd European Breast Cancer Conference today (Saturday 23 March). If the women were younger than 30 when they received the treatment their relative risk was even higher at eight times the normal risk. If the spleen had been removed from these younger women as part of the treatment (splenectomy), then they faced a ten times higher relative risk than the general population, while a family history of breast cancer increased their chances of developing the disease 11-fold above the ge
More Prophylactic Mastectomy News Articles
| © 2008 BrightSurf.com |