The clinical effectiveness and cost-effectiveness of different surveillance mammography regimens after the treatment for primary breast cancer: systematic reviews registry database analyses and economic evaluation

BACKGROUND

Following primary breast cancer treatment, the early detection of ipsilateral breast tumour recurrence (IBTR) or ipsilateral secondary cancer in the treated breast and detection of new primary cancers in the contralateral breast is beneficial for survival. Surveillance mammography is used to detect these cancers, but the optimal frequency of surveillance and the length of follow-up are unclear.

OBJECTIVES

To identify feasible management strategies for surveillance and follow-up of women after treatment for primary breast cancer in a UK setting, and to determine the effectiveness and cost-effectiveness of differing regimens.

METHODS

A survey of UK breast surgeons and radiologists to identify current surveillance mammography regimens and inform feasible alternatives; two discrete systematic reviews of evidence published from 1990 to mid 2009 to determine (i) the clinical effectiveness and cost-effectiveness of differing surveillance mammography regimens for patient health outcomes and (ii) the test performance of surveillance mammography in the detection of IBTR and metachronous contralateral breast cancer (MCBC); statistical analysis of individual patient data (West Midlands Cancer Intelligence Unit Breast Cancer Registry and Edinburgh data sets); and economic modelling using the systematic reviews results, existing data sets, and focused searches for specific data analysis to determine the effectiveness and cost-utility of differing surveillance regimens.

RESULTS

The majority of survey respondents initiate surveillance mammography 12 months after breast-conserving surgery (BCS) (87%) or mastectomy (79%). Annual surveillance mammography was most commonly reported for women after BCS or after mastectomy (72% and 53%, respectively). Most (74%) discharge women from surveillance mammography, most frequently 10 years after surgery. The majority (82%) discharge from clinical follow-up, most frequently at 5 years. Combining initiation, frequency and duration of surveillance mammography resulted in 54 differing surveillance regimens for women after BCS and 56 for women following mastectomy. The eight studies included in the clinical effectiveness systematic review suggest surveillance mammography offers a survival benefit compared with a surveillance regimen that does not include surveillance mammography. Nine studies were included in the test performance systematic review. For routine IBTR detection, surveillance mammography sensitivity ranged from 64% to 67% and specificity ranged from 85% to 97%. For magnetic resonance imaging (MRI), sensitivity ranged from 86% to 100% and specificity was 93%. For non-routine IBTR detection, sensitivity and specificity for surveillance mammography ranged from 50% to 83% and from 57% to 75%, respectively, and for MRI from 93% to 100% and from 88% to 96%, respectively. For routine MCBC detection, one study reported sensitivity of 67% and specificity of 50% for both surveillance mammography and MRI, although this was a highly select population. Data set analysis showed that IBTR has an adverse effect on survival. Furthermore, women experiencing a second tumour measuring >20 mm in diameter were at a significantly greater risk of death than those with no recurrence or those whose tumour was <10 mm in diameter. In the base-case analysis, the strategy with the highest net benefit, and most likely to be considered cost-effective, was surveillance mammography alone, provided every 12 months at a societal willingness to pay for a quality-adjusted life-year of either £20,000 or £30,000. The incremental cost-effectiveness ratio for surveillance mammography alone every 12 months compared with no surveillance was £4727.

LIMITATIONS

Few studies met the review inclusion criteria and none of the studies was a randomised controlled trial. The limited and variable nature of the data available precluded any quantitative analysis. There was no useable evidence contained in the Breast Cancer Registry database to assess the effectiveness of surveillance mammography directly. The results of the economic model should be considered exploratory and interpreted with caution given the paucity of data available to inform the economic model.

CONCLUSIONS

Surveillance is likely to improve survival and patients should gain maximum benefit through optimal use of resources, with those women with a greater likelihood of developing IBTR or MCBC being offered more comprehensive and more frequent surveillance. Further evidence is required to make a robust and informed judgement on the effectiveness of surveillance mammography and follow-up. The utility of national data sets could be improved and there is a need for high-quality, direct head-to-head studies comparing the diagnostic accuracy of tests used in the surveillance population.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

The use of poloxamer hydrogels for the assessment of biofilm susceptibility towards biocide treatments

Poloxamer F127 is a non-toxic, di-block copolymer of polyoxyethylene and polyoxypropylene. Aqueous solutions (30% w/v) show thermoreversible gelation, being liquid at temperatures < 15 degrees C and robust gels at temperatures > 15 degrees C. Chilled poloxamer (30% in tryptone soya broth) was mixed with an inoculum of Pseudomonas aeruginosa (10(4) cfu ml-1) and placed as 100 microliters drops onto separate glass cover-slips. These were placed into sealed Petri dishes containing moistened cotton wool and incubated at 35 degrees C. Viable counts could be performed on the poloxamer gels by transfer of the coverslips to diluents at < 15 degrees C. Growth curves in the gels and in liquid batch cultures were indistinguishable from one another with stationary phase cell densities, being approximately 5 x 10(10) cfu ml-1 in each at 16 h. SDS-PAGE of cell envelope preparations showed the poloxamer-grown cells to exhibit a biofilm rather than planktonic phenotype. Susceptibility towards various concentrations of chlorhexidine, iodine and hydrogen peroxide was assessed for 10 min at 35 degrees C for suspensions of broth-grown cells and for incubated poloxamer-gels (1 and 16 h). The gels were immersed in biocide, on their glass supports, before transfer to neutralizer at 10 degrees C where dissolution was complete within 5 min. Further serial dilutions and plate counts were made. While modest decreases in susceptibility towards all biocides were associated with incorporation of the inoculum with the gel (1 h incubation), substantial changes were noted after prolonged incubation and adaptation to a biofilm phenotype (16 h incubation). The gel populations mimic the localized high cell densities observed in biofilms and will also be subject to the same nutrient and chemical gradients as found within natural biofilms. Thermoreversible gelation enables complete recovery of the test inoculum without further trauma. They therefore provide an effective model for assessing biofilm susceptibility towards biocides and would be suitable for screening programmes.

Differential responses of human tumor-cells to polyunsaturated Fatty-acids - stimulation of proliferation of a colon-tumor cell-line by docosahexaenoic Acid

The potential differential effects of polyunsaturated fatty acids (5-100 mu g/ml) on four human tumour cell lines of different origin and a human fibroblast cell line were investigated. Following 6 days exposure to the fatty acids, gamma linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid, culture growth was almost completely abolished at the highest concentration used. At lower concentrations, the tumour cell lines exhibited a differential sensitivity to the inhibitory effects of the fatty acids on cell number (IC50, breast=lung>melanoma>colon). MRC-5 fibroblast cell numbers were significantly increased at low concentrations of gamma linolenate and eicosapentaenoate, but significantly reduced by docosahexaenoate. These effects on cell numbers were rapid in onset. Following only 2 days exposure to low concentrations of the fatty acids, cell numbers in the breast tumour cell line, MCF-7, were significantly reduced relative to controls. In contrast, the colon cell line, WiDR, was largely unaffected at this time, and in some cases, cell numbers were significantly increased. In the normal fibroblast cell line, cell numbers were significantly reduced by docosahexaenoate at concentrations greater than or equal to 20 mu g/ml. Following only 2 days exposure to PUFA, cell death in the breast cell cultures was maximally increased above controls by 20 mu g/ml of docosahexaenoate, whereas cell proliferation was unaffected at this concentration. In contrast, under these circumstances, cell proliferation in the colon cell cultures was significantly increased by this PUFA while there were only small increases in cell death. Our observations have highlighted the differential responses of human tumour cell lines to PUFAs and documented the stimulation of a colon cell line by certain PUFAs.

Expression of the intermediate affinity interleukin-2 receptor by a human solid tumor-cell line - evidence for functional-activity

Interleukin 2 (IL2) has well recognized pleiotropic effects on the activation, differentiation and proliferation of lymphoreticular cells, mediated via its specific membrane-bound receptors, but its effect on human solid tumour cells is poorly characterised. This study has used the A549 tumour cell line, derived from a human lung carcinoma, to demonstrate the presence of the interleukin 2 receptors (p70/75 beta and/or p55 alpha components) and to document functional activity. Immunohistochemical techniques demonstrated large amounts of the p70/75 beta chain of the interleukin 2 receptor, which is necessary for IL2 internalization, receptor signal transduction and mediation of the biological effects of IL2. In contrast, the p55 alpha chain was detected minimally and sparsely. In addition we documented the presence of IL2 in the nucleus of the A549 cells. The addition of exogenous rIL2 (10-500 IU/ml), to the culture medium of A549 cells over 48 hours resulted in a significant stimulation of DNA synthesis, as assessed by tritiated thymidine uptake. The results were; 9335+/-365, 12669+/-271, 12889+/-255, 19448+/-1427, 20189+/-1004 and 22586+/-1334 CPM, at 0 IU/ml, 10 IU/ml, 50 IU/ml, 100 IU/ml, 250 IU/ml and 500 IU/ml, respectively (means+/-SEM), and were significantly increased when compared with control cultures, p<0.001). These results may have important implications in our understanding of tumour-host interactions and in future strategies involving immunotherapy.