Latest developments on breast cancer treatments

Tristan Manalac
25 Dec 2016
Latest developments on breast cancer treatments

During the period between 1999 and 2008, there have been major changes in the preferences of breast cancer treatment in China, according to an expert who spoke at the recently concluded European Society of Medical Oncology (ESMO) Asia 2016 Congress.

Dr Shinji Ohno, the representative director of the Breast Oncology Center of the Cancer Institute Hospital in Tokyo, was invited to discuss three studies related to breast cancer, treatments and relapse.

The first of three, authored by Qiao Li, et al, investigated the chemotherapeutic drugs used to treat breast cancer patients in China from 1999 to 2008. The study showed how the survival rate of patients improved with increasingly effective chemotherapeutic treatments.

Their graphs showed a higher expected mortality for patients who did not take chemotherapy compared to those on either anthracycline or the cyclophosphamide, methotrexate and fluorouracil (CMF) drug combination.

It was argued in the study that the CMF drug regimen for treating chemotherapy yielded a better survival rate than that of anthracycline.

In the same vein, the study also showed that drug regimens combining Taxotere and Cytoxan (TC) were more effective than those combining Adriamycin and Cytoxan (AC), both in terms of disease-free and overall survival.

In terms of drug usage, there has been an apparent increase in taxane and decrease in anthracycline, at least in the US. In both Medicare and Marketscan cohorts used in the study, sharp changes in the usage of these drugs were seen in the latter parts of 2005.

In China, a similar trend can be observed. Throughout the study period, there was an observed drop in athracycline-based adjuvant and neoadjuvant therapies, and an increase in those based on both anthracycline and taxane.

This, however, is dependent on geographic location. CMF-based adjuvant regimens, for instance, are more common in southwest China while neoadjuvant regimens based on anthracycline only are more common in northwest China.

The data indicate that, over the 10-year study period, there have been major changes in the use of chemotherapeutic regimens in China. This is a reflection of the incorporation of the new evidence and guidelines into clinical practice in China.

The second study, by Yu-Sen Huang, et al, investigated how mammographic breast density might affect the risk of locoregional recurrence of breast cancer after modified radical mastectomy.

A total of 121 pairs of women with invasive breast cancer were recruited. Necessarily, these women should have undergone modified radical mastectomy and have had breast density measurements prior to the operation.

Breast density, according to the study, is influenced by several factors: age, body habitus, genetics, oestrogen use, parity and menstrual cycle phase. Additionally, dense breasts not only decreases the sensitivity of mammographies, but also increases the risk of developing breast cancer.

Thus far, however, there has been no evidence that associates dense breast tissue with increased mortality as caused by breast cancer.

The analysis found that women who had extremely dense (>75 percent density) and heterogeneously dense (between 50 and 75 percent density) breasts had an increased risk of locoregional recurrence of breast cancer. The respective hazard ratios for these were 5.7 and 3.1, with p-values of 0.048 and 0.043.

The study thus pegs dense breast tissue (>50 percent density) as correlated with an increased risk of recurrence in the locoregional area following modified radical mastectomy.

The final study, authored by Olexiy Aseyev, et al, aimed to create a tool for predicting the risk of relapse of locally advanced breast cancer following neoadjuvant treatment. The study was also presented at the ESMO Asia 2016.

For the study, 545 individuals diagnosed with locally advanced breast cancer were recruited. Each patient had received neoadjuvant treatment between 2005 and 2015. The median follow-up period for the study was 49 months.

The endpoints tested for in the study were the relapsing of the disease and the time, in months, it took to relapse.

Overall, 125 or 22.94 percent of the patients experienced relapse. Of these, 94 had distant relapse, 22 had local relapse, and 9 had both distant and local relapse. Overall, the mean time to relapse was 26.06 months.

In constructing the predictive tool, the team had to contend with more than 60 different variables, Dr Aseyev said. Among these were various patient demographic variables, the rate of disease, the positive nature of the disease, the status of the hormone receptors and other relevant clinical factors.

However, the final predictive tool only included five factors, all easily assessed in every clinical centre: residual disease, regional lymph node, inflammatory breast cancer, status of estrogen receptors and adjuvant radiotherapy.

Each patient was then scored on each factor based on the hazard ratio from the Cox regression model, with the scores being compared against a range of scores.

Those who scored anywhere from 0 to 5 were assigned a low risk of relapse, with an average risk of 7 percent. Those with scores from 8 to 12 were, in turn, assigned a high risk of relapse, with an average risk of 51 percent. Those with scores of either 6 or 7 were said to have an intermediate risk of relapse, with a risk of 18 percent.

The study shows that it is possible to individualize the risk of relapse for patients using only five main risk factors. The model also shows that those who score high should be given more proactive and intensive follow-up treatments, Dr Aseyev concluded.

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