Breast cancer: advances in treatment
The American Society of Clinical Oncology (ASCO) brings together the world’s leading cancer experts every year. Attending in Chicago in July 2010, Prof Pierre Fumoleau, Managing Director of the Georges-François Leclerc ‘Fight Against Cancer’ Centre in Dijon (France) gives us an update on the main advances made in the treatment of breast cancer.
Several of the studies presented at the ASCO 2010 annual meeting took an interest in a technique called sentinel node biopsy. Could you give us an introduction to the principles of this procedure?
Prof Pierre Fumoleau: The first step to metastasis development in breast cancer is invasion of the lymph nodes in the underarms. To avoid this, we have long associated the surgical removal of a breast invasive tumour (one that has started to infiltrate the mammary gland) with an axillary node dissection on the affected side (removal of the lymph node chain).
The sentinel node technique, developed in the 1990s, involves taking a biopsy of the first nodes to examine them, and then only carry out dissection if these first nodes are “affected”, in other words, if they contain malignant cells. This less traumatising method reduces problems of lymphoedema (lymphatic obstruction causing localised fluid retention and swelling) in particular.
Is this less traumatising technique as effective as a routine axillary node dissection?
Prof Pierre Fumoleau: Several studies have compared sentinel node biopsy with routine axillary dissection versus sentinel node biopsy and dissection if necessary. Most have reported comparable effectiveness between the two techniques1. The results of the largest ever clinical trial - NSABP 32 - were presented during the ASCO 2010 annual meeting2. Carried out on over 5,600 women for more than 8 years, this study observed no difference between the two techniques in terms of overall survival (number of women who survived at the end of the study), survival without cancer progression or cancer recurrence. These results therefore confirm the benefits of the sentinel node procedure, less traumatising for patients.
If the sentinel nodes are affected, an axillary node dissection is therefore carried out as normal. However, hasn’t this procedure has been called into question by an American study on small tumours?
Prof Pierre Fumoleau: When the tumour is less than 5cm in size and there are no signs of the disease spreading outside of the breast, is axillary node dissection necessary even if the sentinel nodes are positive? No, according to an American study3 on 891 women monitored for almost 6 years. In other words, if the tumour is small and even if the sentinel nodes are positive, the study authors believe that it is pointless to remove the other nodes as no difference has been observed in terms of overall survival or cancer recurrence.
Is this therefore the end of axillary node dissection for these small tumours?
Prof Pierre Fumoleau: No it’s not. Despite the quality of this study, it does have some limitations. Firstly, the number of women who participated remains small (450 women in each group). Secondly, they were only monitored for 6 years, yet we know that late recurrences of tumours can occur after this period. Confirmation by another study will be necessary before practices change in this domain.
Will some of the studies presented at ASCO 2010 change breast cancer treatment in the more or less long term?
Prof Pierre Fumoleau: Two studies are of particular interest:
- During the first stages of treatment, the tumour is analysed by an anatomopathologist to ascertain whether it has particular surface receptors (hormonal receptors and HER2 receptors). The choice of treatment depends on these results, hormone therapy or trastuzumab (Herceptin®) respectively. Italian researchers4 removed liver metastases by biopsy (editor’s note: breast cancer cells which have infected the liver) in 255 women suffering from advanced breast cancer, to find out whether these cells still present the same biological characteristics. They found that many of them had changed status: a hormone-dependant tumour was no longer one, or vice versa; a tumour previously without HER2 receptors was found to present a high number of HER2 receptors. Even if this may be an error in initial analysis, the results have helped to change treatment for some women. It therefore appears of interest to carry out liver biopsies (to study these metastases), particularly if the treatment started is not giving good results. Nevertheless, a liver biopsy remains an invasive procedure which is not to be considered lightly. And metastases are not always located in the liver...
- Another study5, this time on 636 women aged 70+ who had undergone a lumpectomy for a hormone-dependant tumour of less than 2cm, compared tamoxifen-based treatment with tamoxifen plus irradiation. After 12 years, researchers showed that there is no difference in terms of overall survival (only localised recurrences were a little more significant without irradiation). Even though these results merit further confirmation, they do ask the question of how useful irradiation is for these women.
Copyright © 2010 Doctissimo
Get more on this subject…