So said Professor Paul Ruff, head of the division of medical oncology at Wits University, and Dr Georgia Demetriou, senior consultant and head of teaching at Wits.
The pair were speaking ahead of the 15th Prestigious Research Lecture to be held at the university’s Faculty of Health Sciences today.
The latest South African National Cancer Registry data shows more than 2 900 new metastatic colorectal cancer (mCRC) patients are diagnosed each year - with men slightly more predominant than women.
“If you go back to when when I started oncology, what we could offer patients was very limited treatment options.
"And if you look at the standard of studies done (1980s and '90s), the statistics were limited and the patient numbers were small and ethics less rigorous. Since then, the standard of clinical research has improved drastically. Although they have obviously become more difficult and demanding in nature,” Ruff said.
He said in the last 20 years the overall survival rates of metastatic CRC have improved, increasing in some patients from around one year to over three years.
“The major thrust of oncology research in the first part of the 21st century was looking at blood vessel formation - because we know that if you block the formation of tumour cells we can slow the cancer down,” Ruff explained.
In came Bevacizumab - a medication used to treat a number of cancers by slowing the growth of new blood vessels and which, in combination with chemotherapy, became the “mainstay” of treatment for mCRC.
Ruff also talked about antiangiogenic treatments which received exciting results in recent years, such as ramucirumab and aflibercept.
In addition, anti-EGFR monoclonal antibodies such as cetuximab and panitumumab, have been shown to be very active in metastatic CRC patients provided that RAS, a protein in the EGFR signalling pathway, is not mutated.
“Another important issue today is the realisation that the outlook for recovery in CRC is dependent on the position of the tumour on the colon. It appears that people with cancer on the left side of the colon do better than those with it on the right. Currently research is under way to understand the reasons for this,” he continued.
He also added that age is also an important risk factor and that black patients appear to be presenting with CRC at a younger age than white patients.
“There’s a lot of work on that right now... Unfortunately, in the public sector, access to newer medications isn't readily available unless we have clinical trials because biological medicines are more expensive by nature.”
Demetriou, who will be discussing breast cancer treatment advances at the lecture, said that it (breast cancer) was, as a whole, the most common cancer in the country with more than 8 200 women developing it annually, according to the latest available statistics.
“Between 15% and 20% of breast cancer in SA, as well as worldwide, is Her2-positive - a clinically more aggressive subtype of breast cancer - whether it is an early pick-up or a late pick-up - with a higher risk of recurrence and metastatic spread to sites such as the liver, lungs, bone and, sometimes, the brain,” she explained.
Her2, identified in 1985, is an epidermal growth factor that can stimulate breast cancer cell growth.
Demetriou said scientists had moved a long way in the identification of Her2 as well as testing for it, and the development of trastuzumab, a monoclonal antibody and other newer agents, that can be used as a "blocker".
The use of targeted "blockade" drug therapy and, more recently, targeted dual drug therapy, known as "dual blockade", has come a long way in identifying and blocking Her2-positive breast cancer.
“Four landmark studies published in the New England Journal of Medicine in the setting of early stage breast cancer led to the registration of trastuzumab in this setting and showed a 45% reduction in the risk of the breast cancer recurring across the board in these studies which is a massive development in improving patient outcomes,” she explained.
“More recent trials have looked at a dual blockade with two of the key treatment drugs, trastuzumab and Pertuzumab, to try and achieve an improved survival rate with the use of both drugs in the adjuvant (chemo and targeted treatment after surgery) setting,” Demetriou continued.
This was discussed at the American Society of Clinical Oncology Conference in Chicago at the beginning of this month, although there is concern that the small improvement of survival comes with a prohibitive cost.
Pertuzumab is not available in South Africa yet, while it currently costs around R211 920 for a year’s treatment of herceptin in the public sector and is only available in limited circumstances, while in the private sector it is around R550 000.