Limitations of classical/earlier generation PDT

Limitations of Classical/Earlier Generation PDT  

Despite the safety and efficacy of the treatment (3), PDT has only been used on a limited scale in Western countries, mainly to treat skin cancer. The past limiting factors have been cultural and technical:

Cultural

• Chemotherapy, radiation therapy and hormone therapy are well entrenched in most parts of the western world.  However, in China (for example), where there is much less acceptance of toxic therapies, PDT is reported to be used in approx 1,100 clinics·
• The medical fraternity is very slow to take up new therapies. "In medicine there is a 15 year rule. It takes about 15 years for a new, non-conventional therapy to be widely accepted by the medical community” (7)

Technical

There were a number of limitations with earlier photosensitizers:

• Inadequate selectivity for cancer cells, limiting PDT to treating only local tumors. Use of a not very selective sensitizer resulted in much sensitizer present in healthy cells, and the healthy cells may have been damaged by light. Therefore, in the earlier generation of photosensitizer, treating large areas of the body may have resulted in excessive damage to healthy cells.
• Not enough free radicals were produced, i.e. the cancer cell killing capacity was limited;
• Some sensitizers were activated using blue light where the body is not very transparent. This made the therapy ineffective with deeper tumors.