**7. Five year view**

222 Imaging of the Breast – Technical Aspects and Clinical Implication

55+ No 1 1.2 0.0187

<55 No 1 0.9 -0.0036

55+ No 1 2.2 0.0504

Table 3. Estimated recurrence rates in the absence of radiotherapy and absolute reduction in 15-year risk of recurrence by surgery, age, histological type and grade of tumours, from the

older patients with lower stage non-lobular tumours) (Liljegren 2002; Liljegren et al. 1997). One study has found risk of recurrence to be particularly low in those with non-dense breast tissue (Cil et al. 2009). The results here suggest that a significant proportion of patients with small stellate lesions can be considered at low risk, and that some higher risk patients, such as lobular carcinoma cases, may have high local recurrence rates despite radiotherapy.

Another observational study has found, contrary to our results, that radiotherapy is associated with substantially reduced risk of local recurrence in lobular carcinoma (Diepenmaat et al. 2009). There was, however, a comparatively shorter follow up time (median of 7.2 years). Issues such as this may be resolved by delineating the tumour populations in radiotherapy

The point has already been made that small stellate lesions are a good candidate for less aggressive therapy (Smith et al. 2004; Alexander, Yankaskas, and Biesemier 2006). The potential to save almost 70% of patients in this group from the hazards of radiation therapy

trials which have already been conducted, or by carrying out new prospective trials.

Grade Estimated %

 2 0.9 -0.0026 3 1.7 -0.0115 Yes 1 0.4 -0.0114 2 0.9 -0.0360 3 1.7 -0.0748

 2 2.3 0.0570 3 4.5 0.1470 Yes 1 1.1 -0.0030 2 2.2 -0.0084 3 4.2 -0.0235

 2 1.7 -0.0088 3 3.2 -0.0228 Yes 1 0.8 -0.0319 2 1.6 -0.0882 3 3.0 -0.1800

 2 4.2 0.1363 3 8.3 0.2769 Yes 1 2.0 -0.0078 2 3.9 -0.0220 3 7.6 -0.0340

annual recurrence rate without radiotherapy Absolute reduction in 15-year probability of recurrence with radiotherapy

histology

Mastectomy <55 No 1 0.5 -0.0007

Surgery Age Lobular

Breast conserving surgery

final Cox regression model.

is a goal worth pursuing.

These results are observational, and need to be validated.

The results of this observational study suggest that contrary to standard practice, postoperative radiotherapy may not be the ideal treatment for all breast cancers treated with breast conserving surgery, particularly those with good prognosis. This is not to deny the results of the randomised trials and meta-analyses. There is clear evidence from these that radiotherapy reduces local recurrence and improves survival. However, this does not necessarily imply that it is needed in all cases. There is potential for utilising patient and tumour information to assign treatment based on that which is appropriate for the subgroup. This tailored therapeutic approach uses simply obtained specifics, e.g patient age, radiological appearance and tumour histology/grade. It would enable a more accurate riskbenefit analysis to be calculated before prescription of therapies with adverse side-effects such as radiotherapy. It is therefore attractive in comparison with universal provision of radiotherapy to all patients. Before such policies can be implemented, it is essential that we are certain of the risks:benefit ratio for each patient subgroup and therefore these findings must be validated. This approach of investigating the level of benefit to different patient populations may be useful for other cancer therapies with adverse side-effects, with the objective of identifying other areas for improvement as medical oncology progresses to an era of individually tailored treatments.

#### **8. Conclusion**

Radiotherapy is widely used to reduce the risk of local recurrence of breast cancer, particularly after breast conserving surgery. However, radiotherapy to the breast has adverse long-term side effects (risk of heart disease, lung cancer, angiosarcoma, deformation), and therefore it would be useful to identify subsets of patients for whom this treatment is unnecessary. Patients with stellate tumours of 1-14mm have a good prognosis and a high proportion of them might benefit from omitting radiotherapy. A Cox regression was applied to follow up data from 425 such patients and a comparison of local recurrence rates made for different patient groups/tumour stages receiving or not receiving radiotherapy post surgery. These observations suggest that the only group of patients within the 1-14 mm stellate lesions to benefit from radiotherapy are those aged 55 or more, with high grade (2 or 3) disease and non-lobular histology. Radiotherapy may not be beneficial to certain groups with higher risk of recurrence (e.g. younger women or lobular carcinoma) and some groups with low risk of recurrence (e.g. low grade tumours). Further validation using subgroup analyses of trials already performed would be useful.

#### **9. Acknowledgements**

Fieldwork for this study was supported by Cancer Research UK. Analysis was supported by the American Cancer Society through a gift from the Longaberger Company.

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