March 15, 2013

Today, we will be discussing penile cancer and kidney cancer.

Penile cancer is rare in the US because of our hygiene.

• Treatment for penile cancer

1.      Therapy is usually performed in two phases: initial management of the primary tumor and later treatment of the regional lymphatics.

2.      Surgery for primary tumor range from local excision to partial or total penectomy.

3.      Surgery is highly effective, but may not be acceptable to sexually active patients.

• Penile cancers

1.      Can sometimes be treated with topical 5-FU cream, a local excision, or superficial x-rays.

2.      Principle advantage of irradiation for primary lesion is organ preservation.

3.      Superficial x-rays 4500 to 5000cGy in 4 to 5 weeks.

• Male urethra:  external beam

1.      Requires accessories, including bolus, to achieve homogenous dose distribution to the entire organ.

2.      Plastic box with a central circular opening fitted over penis and space between the skin and box filled with tissue-equivalent material; box can be treated with parallel-opposed megavoltage beams.

3.      Alternative to the box is to use a water-filled container to envelop the penis while patient is in prone position.

4.      For lesions of the distal urethra, results with penectomy or radiation therapy are similar to those for carcinoma of the penis, 5-year survival rates of 50% to 60% are comparable.

5.      Most patients with male urethral carcinoma are treated surgically.

6.      More complex device is a Perspex tube that uses vacuum pressure to keep the penis immobile during treatment.

7.      Large fraction size can lead to late tissue damage, so a smaller daily fraction and larger total dose are preferable.

8.      Regional lymphatics treated with bilateral inguinal and pelvic fields.

• Side effects

1.      In almost all patients radiation to the penis produces erythema, dry, & moist desquamation, and swelling of the subcutaneous tissue of the shaft.

2.      These reversible reactions subside within a few weeks with conservative treatment.

3.      Most strictures after radiation appear at the meatus, with a frequency up to 40%.

Kidney cancer

• Renal cell carcinoma

1.      Radiation therapy only when tumor cannot all be excised or upon recurrence.

2.      Treatment volume includes the renal fossa and site of gross recurrence (if any) along with the paraaortic nodal drainage sites.

3.      Doses range from 4500-5500cGy; the usual recommended dose that can be safely given to the upper abdomen is 5040cGy at 180cGy/fraction over 5-6 weeks.

4.      The remaining kidney shouldn’t received doses above 1800cGy.

5.      For a right-sided tumor, a field reduction may be needed at 3600-4000cGy to ensure no more than 30% of the liver is irradiated at a higher dose.

6.      Normal dose for spinal cord should be limited to 4500cGy.

7.      Isocentric parallel-opposed AP/PA fields.

8.      Higher energy (10+MV) are used.

• Renal pelvic & ureteral carcinoma

1.      Treatment portal usually includes the entire renal fossa, ureteral bed, and ipsilateral bladder trigone; because of high nodal involvement, the portal should also include paraaortic and paracaval areas.

Like renal cell carcinoma, the dose is limited by the tolerance of normal tissues in the treatment field.

Reflections:
Penile cancers are less likely to be a problem here in the USA because we generally circumcise our boys and we generally have good hygiene.  Why does hygiene affect penile cancer?  I think that perhaps internal cancers like prostate, rectal, breast, brain, esophageal, etc. get cancer because the white blood cells get overwhelmed with their job of getting rid of cancer cells.  While the penile cancer gets help internally and externally through good hygiene.