Interventional oncology: A new era of minimally invasive techniques

• Open surgery to remove cancer is not always possible and associated with complications.
• In some cases, minimally invasive procedures known as locoregional therapies (LRTs) offer an alternative cancer treatment.
• A leader in the field of interventional oncology, Professor Thomas Vogl’s research at Frankfurt University Hospital in Germany compares survival rates for different LRTs.
• Looking back over the last 26 years, Vogl and his team assess the progress of these therapies in liver cancer and liver metastases of colorectal cancer, breast cancer, and others.
• This first-of-its-kind study offers initial insight into therapies with the best survival rates and outlines future research directions for this developing field.

Recent advances in technology and imaging have expanded the use of interventional radiology for cancer treatment. These oncological treatment strategies are minimally invasive procedures, and, importantly, offer an alternative to open surgery. The subfield of interventional oncology has gained traction in the last few decades with the development and use of different locoregional therapies (LRTs).

To assess progress in this field, Professor Thomas Vogl takes a retrospective look at thermoablation techniques, their development, advancement, and use at Frankfurt University Hospital, Germany. This novel research focuses on breast cancer liver metastasis (BCLM) and liver cancer (hepatocellular carcinoma) to compare LRTs, demonstrating that the therapy type used predicts patient survival.

His work provides a much-needed knowledge base and a foundation for future investigation in an area of growing research interest. Recent convening of a consensus panel by the Society of Interventional Radiology Foundation, of which Vogl was part of, identified research priorities and future directions for breast cancer treatment using these minimally invasive technologies.

What are minimally invasive techniques?

Interventional radiology methods involve puncturing the skin with a needle or entering body orifices to access underlying tissue or arteries to diagnose conditions or deliver treatment. Guided by medical imaging, such techniques enable specialists to deliver treatment more accurately, leading to better patient outcomes, reduced loss of tissue, and quicker recovery time. Among other applications, these techniques can break down clots following a stroke, obtain tissue biopsies, and treat vascular diseases affecting blood vessels as well as cancer.

Vogl’s research centres around the use of such techniques in interventional oncology, specifically BCLM and hepatocellular carcinoma. Breast cancer is the most common cancer in women and has several subtypes, which differ in prognosis and treatment. Primary breast cancer refers to cancer that has not spread; unfortunately, in half of breast cancer patients, the cancer spreads to other parts of the body, known as metastases. About half of patients with metastatic breast cancer also develop tumours in the liver – these are known as hepatic metastases. These patients have poor prognosis and limited surgical options. Liver cancer is the third leading cause of cancer deaths, with liver resection (removal of cancerous part of the liver) or liver transplant possible treatment options. However, since most patients cannot be considered for these treatments, alternative therapies are urgently needed.

Two types of minimally invasive procedures to treat cancer are procedures blocking blood supply to a tumour to shrink it (transarterial chemoperfusion, TACP and transarterial embolisation, TAE) and applying extreme heat or cold to the tumour to kill the cells (tumour thermoablation). Transarterial embolisation is further categorised into procedures that simultaneously deliver chemotherapy to the tumour (transarterial chemoembolisation or TACE) and radioembolisation, which uses small beads to release radiation to the tumour. Such procedures target the tumour but also have secondary effects elsewhere in the body, including other tumour sites.

Vogl’s novel study reports retrospectively on three different LRT procedures: laser interstitial thermal therapy (LITT) and microwave ablation (MWA), both thermoablation procedures, and TACE. LITT is a time-consuming procedure that uses a laser light to break down the secondary liver tumours and imaging to monitor the process. MWA uses an electromagnetic field to destroy tumours. Lastly, TACE delivers high doses of chemotherapy to the tumour. Such therapies can be applied on their own or, alternatively, TACE can be administered in combination with LITT or MWA.

Looking back

Because the study spanned such a long time period, treatment methods changed from LITT applied in the earlier years to MWA later on. Vogl acknowledges that such changes in the techniques used, their evolution and improvements may have influenced study results. Still, a key finding was that survival rates differ depending on the treatment type used in both patients with BCLM and hepatocellular carcinoma.
In breast cancer liver metastasis, MWA showed by far the best average survival rates.

Survival rates differ depending on the treatment type used in both patients with BCLM and hepatocellular carcinoma.

However, this group consisted of very few patients, meaning the result should be interpreted with caution. In addition, these patients had five or fewer lesions of smaller size and, therefore, a less severe stage of cancer compared to other groups. Combination treatment of MWA and TACE demonstrated the next best survival times with better three- and five-year survival percentages compared to the other groups, suggesting its potential for treating BCLM.

Results were similar for hepatocellular carcinoma, with MWA having the best median survival time and survival rates followed by MWA and TACE combination treatment, which was only exceeded by LITT and TACE combination for one-year survival rate. In both types of cancer, the TACE group had the worst survival time and rates, but this must be interpreted carefully because the TACE group had patients with more advanced cancer compared to other groups.

Despite its limitations, this research gives us a long-term overview of progress in this field and how different therapies affect patient survival.

Looking forward

The study did not account for different patient characteristics and other factors contributing to survival rates, such as the severity of liver function and the number and size of tumours. This means their contribution or influence on the survival rate is unknown. Age was accounted for, so we know that age alone doesn’t drive these differences in survival rates. Acknowledging these limitations, Vogl now calls for future randomised trials comparing these treatments that detail the size and location of liver tumours and consider other patient factors. Such prospective studies will further our understanding of these differences to optimise cancer treatment.

Despite its limitations, this research gives us a long-term overview of progress in this field and a valuable start in demonstrating how different therapies affect patient survival. With key research priorities for LRTs in breast cancer recently identified by the Society of Interventional Radiology Foundation, this study lays the groundwork and provides a platform for future research in this important and ever-evolving field.