Axillary node dissection in patients with breast cancer diagnosed through the Ontario Breast Screening Program: a need for minimally invasive techniques.

OBJECTIVE

To determine the role of axillary node dissection by studying patient and tumour characteristics of invasive breast cancer through the Ontario Breast Screening Program (OBSP).

DESIGN

A retrospective evaluation.

SETTING

The London, Ont., branch of the OBSP.

PATIENTS

Three groups of women seen were studied: 50 women with screen-detected breast cancers, which were palpable and detected by the nurse-examiner, 62 women with occult screen-detected breast cancers and 353 age matched women with invasive breast cancer from the LRCC prospective database, who served as controls.

MAIN OUTCOME MEASURE

The proportion of involved axillary nodes within the 3 groups based on patient and tumour characteristics.

RESULTS

Twenty-five (22.3%) of the 112 women had screen-detected tumours less than 1 cm in dimension, but only 1 had an involved axillary node. Twelve (19%) of the 62 women with occult screen-detected tumours had involved lymph nodes compared with 17 (34%) of the 50 women with palpable screen-detected cancers (NS). In the control group tumour dimension less than 1 cm versus 1 cm or larger had a marked effect on the probability of axillary node involvement (12.5% v. 40.7%, p = 0.001). In the palpable screen-detected group 3 times as many women with outer quadrant or central lesions had involved nodes as those with inner quadrant lesions (38% v. 12%) and for those with a family history of breast cancer almost twice as many had involved axillary nodes. In occult screen-detected patients there was more nodal involvement in patients aged 60 years or less than in those older than 60 years (35% v. 10%, p = 0.042); only 4 of 41 patients older than 60 years had involved nodes at surgery. A significant difference in nodal involvement was found with respect to high or intermediate grade versus low grade lesions in the occult group (44% v. 12%, p = 0.033). In the control group, tumour grade (intermediate and high [45.3%] v. low [20.0%]) and hormone replacement therapy (HRT) (current or recent use [56.5%] v. no use [34.5%]) were significant findings (p < 0.001 and p = 0.005 respectively).

CONCLUSIONS

Women older than 60 years with tumours smaller than 1 cm had a low probability of nodal positivity (0% to 8.7%), but there is insufficient information in this group to give a 95% or better prediction of nodal status at the time of surgery. Studies of minimally invasive techniques such as sentinel node biopsy are needed in this group to minimize surgical morbidity in these women who, as a result of early diagnosis, have an excellent long-term outlook.