What is bladder preservation and who is eligible for bladder
preservation?
Can we avoid surgery in bladder cancer?
Complete removal of the urinary bladder, prostate which is also referred to
as radical cystectomy is the traditional standard in patients with muscle
involving bladder cancer. However, in the last few decades, certain groups
of patients can be treated with radiation and chemotherapy and can achieve a
cure without the need for the removal of the urinary bladder. This is
usually done after complete transurethral resection of the bladder tumor.
The trimodality treatment which is a combination of cystoscopic resection of
bladder tumor, radiation therapy to bladder and chemotherapy is considered
for a significant proportion of patients of bladder cancer in the best
centres worldwide.
This approach is referred to as bladder preservation where the patient’s
native bladder is preserved and there by the patient can micturate
naturally. Although this has been extensively tested, it is now considered
as an alternate standard for a select group of patients. The patient
selection for this type of treatment requires a multidisciplinary approach
by a team consisting of urologists, radiation oncologists, medical
oncologists, pathologists and radiologists. Patient compliance for
surveillance of the urinary bladder is also taken into account during this
approach.
Radiation therapy for bladder cancer is a challenging treatment due to
continuous alteration of bladder volume, shape and size. Precisely that is
the reason for the requirement of daily image guidance to treat bladder
cancers with radiation therapy. Daily image guidance consists of CT imaging
on the treatment unit.
Treatment planning for Bladder cancers consists of Simulation with a
pre-specified bladder protocol which consists of intake of a particular
amount of water before a pre-specified interval of time. After the optimal
bladder and bowel preparation, patient is taken up for a planning CT scan.
Treatment is delivered under strict daily image guidance.
The external beam radiation therapy for bladder cancers can be delivered with
either of the techniques:
- 3-dimensional conformal
radiation therapy (3-DCRT)
- Intensity-modulated
radiation therapy (IMRT)
- Volumetric Modulated Arc
Therapy (VMAT)
- Helical Tomotherapy
- Proton beam therapy
Several studies have shown that IMRT/VMAT/Tomotherapy is better compared to
3-DCRT in their ability to restrict doses to normal, healthy structures such
as the small bowel, rectum and pelvic bone marrow.
Proton therapy for bladder cancer
Proton
therapy is a highly sophisticated form of radiation
therapy that delivers doses to the target structures and reduces doses to
the surrounding healthy normal tissues. This, in turn, can reduce doses to
the normal structures like the small bowel, rectum, prostate, uterus,
ovaries, fallopian tubes and bone marrow. In bladder cancers, there is
emerging data to suggest that proton therapy is feasible in patients of
urinary bladder cancers and can potentially limit the doses to healthy
normal structures as mentioned above. The dosimetric study done at our
centre, shows that proton therapy can potentially reduce the dose to small
bowel, rectum and pelvic bone marrow. This is extremely useful and crucial
in elderly or frail patients. This technique also could be considered for
patients with unusual anatomy or tumors with unusual locations. Proton
therapy can also be considered in younger patients as the likelihood of
development of secondary malignancies is significantly low compared to other
photon-based conformal techniques such as IMRT/VMAT/Tomotherapy. It can also
be used during scenarios like re-irradiation to selectively treat the
bladder tumors. With proton beam therapy, the patient can maintain their
current quality of life both during and after treatment.