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2.7 Male Reproductive System: Testicular Cancer Cheat Sheet (DRAFT) by

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Anatomy

Testicular cancer presen­tation will often be via a painless swelling, or mass in the scrotum. Sometimes there is localised discomfort or pain, with an associated heaviness.
If there is pain in the abdomen this can be suggestive of pelvic or abdominal metast­ases, and should be invest­igated accord­ingly. Elevated serum markers should be assessed. These can help the physician distin­guish between different types of testicular cancers.
The testicles (testes) are two small, oval-s­haped organs located behind the penis in a skin sack called the scrotum.
Each testis lies within a fibrous capsule known as the tunica albugi­nea, within the scrotum.
The testicles are located outside the body because sperm develop best at a temper­ature several degrees cooler than normal internal body temper­ature.
The germ cells inside the semini­ferous tubules (sertoli cells) create sperm. The sperm move into the epididymis where they mature. They are stored there for a few weeks until they eventually move up the vas deferens to combine with fluids from the prostate and seminal vesicles to form what you normally think of as semen. The whole process takes about 7 weeks.
The leydig cells distri­buted throughout the testicle are the body's main source of testos­terone. Testos­terone, the male sex hormone, is essential to the develo­pment of the reprod­uctive organs and other male charac­ter­istics such as body and facial hair, low voice, and wide shoulders. Without enough testos­terone, a man will probably lose his sex drive and suffer from fatigue, depres­sion, hot flashes and osteop­orosis.
Lymphatics play an important part in the management of testicular cancer patients.
The lymphatics directly from the testes follow the spermatic cord, through the inguinal ring, along the iliac nodes and to the para-a­ortic nodal chain. These lymphatic chains ultimately determine the radiation fields.

Epidem­iology and Aetiology

Testicular tumours are rela­tively rare, repres­enting approx­imately 1% of all cancers.
In men aged between 20 and 34 it is the most common cancerand most common cancer killer
It is associated with cryp­tor­chi­dism, which is maldescent of the testes from the abdomen. There is an increased risk 10 to 40 times higher.

Pathology

The breakdown of the tumour types expected for testicular tumours are 95 % Germin­al, and the remainder non-ge­rminal.
The germinal tumours are formed from the germ cells, which form sperm within the testicles.
70 % of germinal tumours are seminoma, and the rest are teratomas.
Over the age of 50 tumours tend to be of non-germ cell origin.
Seminoma are sensitive to radiation and often present early at stage 1 where an Orchid­ectomy is performed and then prophy­lactic para-a­ortic node irradi­ation is delivered.
Teratoma would be treated with cytotoxic chemot­herapy as this is a chemos­ens­itive structure and because there is greater chance of distant spread at presen­tation.

Spread

Seminoma is very pred­ict­able in its spread, and at presen­tation regional lymph nodes will be present in 25 % of cases for seminoma, 40 % for teratomas, and 50 % for embryonal carcin­omas.
Spread is most commonly in the para-a­ortic lymph node group, Local spread may be present to the epididymis and spermatic cord.

Diagnostic work-up

General - history and physical examin­ation
Bloods - FBE, serum assays
Medical Imaging - Test­icular ultras­ound is the first procedure for scrotal abnorm­ality, followed by chest imaging and CT of the abdome­n/p­elvis to assess nodal involv­ement.
Surgery consists of an inguinal orchid­ect­omy, where the affected testicle is removed through the groin. This is both a diag­nostic and therap­eutic proced­ure.
The complete removal means an accurate diagnosis can be made through histop­ath­ology and the primary disease has been removed from the patient.
If the surgeon removed all or part of the testes through an incision in the scrotum, then there would be a high risk of seeding within the scar. This technique would also disrupt normal lymphatic flow, altering the natural history of the disease. If partial removal were done, there would be a high risk of local recurr­ence or continued growth of the primary disease.

Staging

There are a number of staging systems used for testicular cancers.
*he Royal Marsden system is the most widely used one.
The Marsden system, it is broken up into 4 stages.

The Royal Marsden staging system

Management

For non-se­minomas and patients with advanced disease, a radical orchid­ectomy and chemot­herapy will be admini­stered.
Chemot­herapy regimes have improved consid­erably for non-se­minoma tumours in the last couple of decades. Therefore after surgery, Platin­um-­based multi-­agent chemot­herapy will be delivered to the patient.
Radi­oth­erapy will not play a role in the management unless there is a large residual mass postch­emo­the­rapy.
For pure semino­ma, surgery via orchid­ectomy will be undert­aken. This is followed by radical radiot­her­apy. Seminoma is highly sensitive to radiation; therefore high doses are not required to be tumour­cidal. This presents as an intere­sting scenario for the radiation oncolo­gist, as these men are young and easily curable (greater than 90 % cure rate). Yet there are a number of critical structures that we will need to discuss.

Simulation

The radiation fields that are used to treat testicular cancer will be dependent upon the disease stage, the admini­str­ation of chemot­herapy and the radiation oncolo­gist’s prefer­ence.
There are usually three options:
For early stage disease only the para-a­ortic nodal group is irradi­ated.
For further advanced disease, a dog-leg technique will be used to include the iliac nodal group on the ipsila­teral (affected) side.
With bulky disease in the para-a­ortic it is possible that the contra­lateral pelvis will be irradiated - an “inverted Y” technique. There will be a central pelvic shield to minimise toxicity to the bladder and bowel.
The treatment technique for both the ‘dog­-leg’ and abdomen techni­ques is using AP/PA photons.
The energy can be dependent on the patients’ AP separa­tion, ranging from 6 to 18 MV.
The patient will be positioned supine on carbon fibre, with a neck support, bolster under knees and ankle support to ensure reprod­ucible leg position.
The radiation fields are designed based on the patient’s lymphatic chains. Everyone’s lymphatics are slightly different, so we need to know where they are.
The classic dog leg techni­que has UL field size is set at T10. The field width is approx­imately 9 to 12 cm in the para-a­ortic region, and 2 cm coverage either side of the ipsila­teral pelvic nodes. This is achieved by angling at the level of the fourth and fifth lumbar vertebrae towards the affected side.
The Lower level is at the top of the obtu­rator foramen, but there is no need to include the surgical scar within the field unless the is a testis capsule was compro­mised and there risk of seeding. The radiation oncologist may like to see a radi­o-o­paque marker along the scar so that it is visu­alised on CT. Most often that not, the LL will run about half way through the scar
Para­-aortic strip
If the radiation oncologist has prescribed radiation to the abdomen only, similar inform­ation to the dog-leg technique will need to be acquired.
The field width is normally 8 – 10 cm wide that may not require any shielding. The upper level of the field will again be the junction of T10 and T11, with the lower level the junction of L5 and S1. There will be little to no shielding required for this technique, so an isoc­entric techni­que is suitable.
The inform­ation to be acquired at simula­tio­n/p­lanning for both the dog-leg and para-a­ortic techniques are essent­ially the same, as follows:
-Tattoo positions (centre dependant) eg isocentre, ½ AP laterally, TOX/ML, UBP/ML
-Stretch TOX (Tip of xiphi-­ste­rnum) to UBP (upper border of pubis)
-UBP – BOP (Base of penis)
-A planning CT throughout the treatment volume will be acquired. This will be used to delineate the kidney volume and the field definition for the patient.
Supr­a-d­iap­hra­gmatic disease
It is unlikely that we will treat above the diaphragm for testicular cancer. If we were to treat a residual mass, the field dimensions are:
-Lateral edges to cover the rib cage
-superiorly is 2 cm above palpable disease
-inferiorly is the 10th rib
-similar doses as the abdomen 25/20/5, with boosts to any bulky disease in the neck or medias­tinum up to a dose of 30 - 40 Gy.

Typical field borders for dog-leg technique

Planning

The planning for these patients is not usually complex, as the technique is just opposed photon fields.
From the CT, the kidneys will be marked.
Figure A (lower image) is a DRR of a patient that was planned for a dog-leg technique for Seminoma. Notice the long field length, the heavy shielding (repre­sented by the horizontal lines), and the partial irradi­ation of the kidneys can be seen in the upper planning images. There is a higher risk of disease on the ipsila­teral side within the para-a­ortic region, so there is greater coverage on that side. Notice how there is slightly more kidney within the field on the right side compared to the left.
A senior member of the planning staff will check the data:
The isocentre is in the correct position;
The dose is even across the treatment volume;
Dose to critical structures - Left and right kidneys;
Correct field size, monitor units, patient position, TD used in the calcul­ations
Once the plan has been checked, and everything is satisf­actory, the patient is ready to commence treatment.

Planning data

Treatment

Since the tumour type is partic­ularly sensitive to radiation, large doses do not need to be prescr­ibed.
Dose between 24 and 30 Gy in 1.5 -1.6 Gy per fracti­on.
If there is a persistent mass, then a boost will be delivered to an extra 5 - 10 Gy.
It is just as well that we can deliver low daily doses since it is such a large area to be treated, with the pote­ntial for signif­icant treatment toxici­ty. As with most radiation therapy techniques there are some critical structures present:
-The cont­ral­ateral testes - probably the most sensitive.
-Kidneys - will be shielded as much as possible while covering the nodal groups.
-Bowel - can’t do much about this - medication as required.
If the tumour is sensitive to radiation, it follows that the testis is sensitive to radiation also.
1 - 2 Gy before sterility is induced
Most patients are informed that it may take a while before they can conceive. Apart from shielding to the lowest dose possible, for young men who wish to have children, sperm banking is advised.
Usually a FBE (Full blood examin­ati­on) will be performed at simulation to establish a baseline on blood counts. Bloods will then be taken weekly through out the treatment from there.
When para-a­ortic nodes are being treated alone, then there is little bone marrow within the radiation fields, but a dog-leg will irradiate a fair amount of the pelvis, which will affect the bone marrow and may alter the blood work up.
Acute side effects: Signif­icant erythema is not expected, due to the low doses, nausea and diarrh­oea are extreamly likely due to the sheer size of the fields, some tire­dness may be experi­enced after about two weeks of treatment.
VERI­FIC­ATION
Weekly imaging will be a minimum for these patients; many clinical centres may acquire images each fraction
Due to the close proximity of the fields to the kidneys, and their relative sensit­ivity to radiation, any lateral movement of the fields will be watched closely.

Compli­cations

Late toxici­ties:
Dyspepsia (a common condition and usually describes a group of symptoms rather than one predom­inant symptom.) i.e Belly pain or discom­fort. Bloati­ng.N­ausea. Loss of appetite. Heartburn. Burping. Regurg­ita­tion.
Peptic ulcers
Intestinal obstru­ction
Gastritis (a group of conditions with one thing in common: inflam­mation of the lining of the stomach.)
Impaired hormonal function
Sperma­tog­enesis impari­ment.

Follow up

The radiation oncologist will follow up the patient around six weeks post completion of the radiation therapy.
After six weeks any radiat­ion­-in­duced side effects should have subsided, and there should be some indication of tumour response.
  

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