Cell Carcinoma - Metastasis to Bone
images are from a 75 year old man with a large painful scapular mass,
which proved to be a renal cell cancer metastasis. He had complete
resection of this mass and now has a chance for long term survival, a
prospect not enjoyed by most patients with metastatic adenocarcinomas.
Although renal cell cancers rank as the approximately sixth most
common site of origin of metastatic deposits in the skeleton, this
tumor has several unique features that increase its significance.
First, the metastatic deposits may occur many years after the primary
tumor has been treated. This means a patient who seems to be cures
after a RCCA is removed from the kidney needs to be monitored for up to
ten years for possible bone metastasis.
Second, RCCA metastases may occur as a solitary focus of disease, and
as such an en bloc
surgical resection of a solitary metastasis may render the patient free
of cancer and offer hope for a cure. These patients have been shown
to enjoy significantly better survival if aggressive treatment is used.
Palliative surgery for these solitary metastatic deposits is not indicated
and may lead to spreading the cancer. Instead, the lesion should
be evaluated by an experienced orthopaedic oncologist for possible curative
Although the number of cases of this cancer is proportionally small, the
tumor has a high avidity for bone and thus creates relatively large number
of bone lesions. Patients are usually over 40, and the average age is
around 55. Patients may have no other manifestation of cancer other than
their painful bone lesion. Because the primary tumor can grow fairly large
without creating local symptoms such as flank pain or a mass in the abdomen,
kidney cancer often presents only when a metastasis develops. Hematuria
is also a common sign, but small amounts of blood in the urine cannot
be detected without a urinalysis When a patient has a metastasis
and no site of origin can be found (a metastasis of unknown origin)
the most likely site is the lung or kidney.
Pain is the most common presenting symptom. Pathological fracture
rarely occurs without a history of a few weeks or months of increasingly
severe pain. In some cases the patient has tried to ignore or deny
the symptoms. Sometimes a painful bone lesion is thought to be a
"muscle pull" or a "sprain" and strong pain medicines
are prescribed, allowing the patient to continue to tolerate very severe
pain before the true nature of the problem is discovered. Systemic symptoms
may also occur, such as hypercalcemia. An occasional patient may
have hypertesion from the tumor affecting the renin-angiotensin pathway.
Kidney cancer metastasis most commonly affects the spine, ribs, pelvis,
and proximal long bones. Kidney cancer may metastasize extremely late
after the treatment of the primary lesion, up to ten years or more.
Why the tumor seems to lay dormant for so long and then suddenly pop up
in the bone is not known. Another unusual feature of this lesion is its
extremely aggressive appearance and behavior in some cases. Lesions
may be large and appear as a "blowout"
of the particular bone involved. Kidney cancers are more likely
to become "hideously large" than other lesions, due to their
propensity to extend massively in the soft tissues surrounding the bone.
Since the kidney is comprised of mostly blood vessels, kidney cancer metastases
may also have a rich blood supply, and may bleed extensively (even audibly)
after a simple biopsy. When you see a patient over age 40 with hematuria
and a large blow-out bone lesion, think kidney cancer.
Kidney cancer with metastasis to bone can be a very aggressive tumor and
patients with multiple bone lesions at presentation have an unfavorable
prognosis. Radiation is not very effective in palliating this lesion,
and no conventional chemotherapy is available. Advanced cancer centers,
like the University of Massachusetts and others have ongoing research
and clinical trials ongoing. I believe all patients should be started
and maintained on bisphosphonates as soon as a diagnosis of metastasis
to bone is confirmed. The average survival after the diagnosis of
metastasis to bone is about 12 - 18 months.
A few selected cases have been associated with prolonged survival with
appropriate treatment. Patients who present with a SINGLE bone metastasis,
whose primary tumor can be resected with negative margins, may be treated
with curative intent. This means these patients have a chance for
a cure, and "palliative" care is not appropriate in these special
cases. The prognosis is even more favorable if there has been a
prolonged period between the treatment of the primary tumor and the discovery
of the metastasis. Kidney cancer is one of the few types of metastatic
adenocarcinoma that may be cured by surgery. Physicians unfamiliar
with these recent developments in the treatment of this disease should
consider referring the patient to a regional or national cancer center.
When there are several sites of bone metastasis, treatment follows general
principles. Orthopedic stabilization of weakened bones should be
done promptly, before fractures can occur. Patients should receive
complete treatment according to their wishes and the extent of the disease.
Orthopaedic stabilization of actual or impending pathological fractures
should not be withheld unless the patient cannot tolerate anaesthesia
or would definitely not be benefited by surgery. The pain relief that
is expectedfrom stabilization of damaged bones is a good enough reason
for surgery, even if the patient cannot enjoy a functional benefit, such
as increased walking ability.