<PAGE>


                         ASSIGNMENT OF AND AMENDMENT TO
                       THE PROFESSIONAL SERVICES AGREEMENT
                         FOR RADIATION THERAPY SERVICES
                                     BETWEEN
                     USCC HEALTHCARE MANAGEMENT CORPORATION,
                     RADIATION ONCOLOGY MEDICAL GROUP, INC.
                                       AND
                       THE PERMANENTE MEDICAL GROUP, INC.

THIS ASSIGNMENT OF AND AMENDMENT TO AGREEMENT ("Assignment and Amendment") is
made and entered into as of August 1, 2000, by and between The Permanente
Medical Group, Inc., a California professional medical corporation ("TPMG"),
Radiation Oncology Medical Group ("ROMG"), a California professional medical
corporation, USCC Health Care Management Corporation, a California corporation
("USCC"), USCC Medical Group-CA, Inc., a California professional corporation
("USCCMGCA"), and The USCMC-USCC Partnership, a partnership between US Cancer
Management Corporation and USCC ("PARTNERSHIP").

                                   WITNESSETH:

A.    Contractor and TPMG have heretofore entered into an agreement effective
August 1, 1999, for Contractor to provide Radiation Therapy Services for Members
(the "Agreement").

B.    The parties hereto desire to amend the Agreement in the manner hereinafter
set forth.

NOW THEREFORE, the parties agree as follows:

A.    Effective August 1, 2000, the Agreement is amended as set forth below.

B.    All other terms and conditions of the Agreement are to remain the same.

                I. ASSIGNMENT AND AMENDMENT #1 - STOCKTON CENTER

A.    RECITALS ARE AMENDED AS FOLLOWS:

      1.    SECTION H is added as follows: "H. It is the parties' understanding
      that Contractor has developed a new medical group, Johnson and Tepperman
      Medical Group, Inc., d.b.a. USCC Medical Group - CA, Inc. ("USCCMGCA"),
      for Services provided at the Stockton Center (St. Teresa Comprehensive
      Cancer Center). At this time, ROMG ("Assignor-1") desires to assign its
      interest and obligations under this Assignment and Amendment, as related
      to the Stockton (St. Teresa) Center, to USCCMGCA ("Assignee-1")."

B.    TERMS OF THE AGREEMENT ARE AMENDED AS FOLLOWS:

NOW, THEREFORE, in consideration of the mutual promises set forth herein and for
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the parties agree as follows:

      1.    ASSIGNMENT. Assignor-1 hereby assigns and transfers all right, title
      and interest in and to the Agreement, for the Stockton Center, to
      Assignee-1, effective as of February 22, 2000.


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      2.    ACCEPTANCE OF ASSIGNMENT. Assignee-1 hereby accepts assignment and
      transfer of all right, title and interest in and to the Agreement, and
      expressly assumes and agrees to perform and be bound by all terms,
      conditions and obligations of Assignor-1 under the Agreement for Services
      provided at the Stockton Center.

      3.    ASSIGNEE-1 REPRESENTATIONS AND WARRANTIES. Assignee-1 represents and
      warrants that Assignee-1 (a) has the authority to execute this Assignment
      and Amendment, and (b) has assumed all obligations and liabilities of
      Assignor-1 relating to the Stockton Center arising under or related to the
      Agreement arising on or after February 22, 2000.

      4.    ASSIGNOR-1 REPRESENTATIONS AND WARRANTIES. Assignor-1 represents and
      warrants that no services were provided under the Agreement as part of the
      Stockton Center before February 22, 2000 and, thus, no tail insurance for
      prior periods is required.

      5.    TPMG CONSENT. TPMG hereby consents to the assignment and assumption
      described in this Assignment and Amendment.

      6.    NOTICES. The parties hereby agree that all notices regarding the
      Stockton Center required under the Agreement to be directed to Assignor-1
      shall henceforth be directed to Assignee-1 at the following address:

                           USCC Medical Group - CA, Inc.
                           c/o US Cancer Care
                           700 Ygnacio Valley Rd., #300
                           Walnut Creek, CA  94596

      7.    PAYMENT BY KP. The parties acknowledge and agree that all payments
      due and owing from KP to Assignor-1 pursuant to the Agreement for the
      Stockton Center shall hereinafter be made to Assignee-1, provided,
      however, that KP's payment (a) to Assignor-1 of amounts owing to
      Assignee-1, or (b) to Assignee-1 of amounts owing to Assignor-1, shall be
      resolved between Assignor-1 and Assignee-1 without liability on the part
      of KP.

      8.    BINDING ON SUCCESSORS. The terms of this Assignment and Amendment
      shall be binding on the parties' successors and assigns.

      9.    COUNTERPARTS. This Assignment and Amendment may be executed in two
      or more counterparts, each constituting an original and all taken together
      constituting one and the same document.

      10.    DESIGNATION. The parties agree that each reference in the Agreement
      to ROMG shall now also refer to USCCMGCA. The term "Contractor" shall
      jointly and separately refer to USCC, ROMG and USCCMGCA.

           II. ASSIGNMENT AND AMENDMENT #2 - SAN RAFAEL, SANTA ROSA,
                               AND FUTURE CENTERS

A.    RECITALS ARE AMENDED AS FOLLOWS:

      1.    SECTION I is added as follows: "I. USCCMGCA is a California
      professional medical corporation that provides certain outpatient
      radiation oncology services in facilities and with equipment owned or
      leased by USCC. USCCMGCA's T1N number is: 77-0536884."

      2.    SECTION J is added as follows: "J. It is the parties' understanding
      that USCC has developed a new partnership ("PARTNERSHIP") with US Cancer
      Management Corporation. ("USCMC") for the future development of Services
      for TPMG, including the currently planned San Rafael and Santa Rosa
      Centers. A copy of the PARTNERSHIP's agreement is attached as Addendum A.
      At this time, USCC ("Assignor-2") desires to assign its interest and
      obligations

<PAGE>


      under the Agreement, as related to the San Rafael and Santa Rosa Centers,
      and such future Centers that the parties desire to develop, to PARTNERSHIP
      ("Assignee-2").

      3.    SECTION K is added as follows: "K. USCMC is a Delaware corporation.
      USCMC's T1N number is: 68-0451110. PARTNERSHIP owns and leases outpatient
      radiation oncology facilities and equipment and, provides certain
      administrative services to ROMG USCCMG-CA and TPMG. PARTNERSHIP's T1N has
      been applied for and will be provided to TPMG after receipt."

B.    TERMS OF THE AGREEMENT ARE AMENDED AS FOLLOWS:

NOW, THEREFORE, in consideration of the mutual promises set forth herein and for
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the parties further agree as follows:

      1.    ASSIGNMENT. Assignor-2 hereby assigns and transfers all right, title
      and interest in and to the Agreement, for the Santa Rosa and San Rafael
      Centers and such future Centers that the parties develop, to Assignee-2,
      effective as of August 1, 2000.

      2.    ACCEPTANCE OF ASSIGNMENT. Assignee-2 hereby accepts assignment and
      transfer of all right, title and interest in and to the Agreement, and
      expressly assumes and agrees to perform and be bound by all terms,
      conditions and obligations of Assignor-2 under the Agreement for Services
      provided at the Santa Rosa and San Rafael Centers and such future Centers
      that the parties develop.

      3.    ASSIGNEE-2 REPRESENTATIONS AND WARRANTIES. Assignee-2 represents and
      warrants that Assignee-2 (a) has the authority to execute this Assignment
      and Amendment, and (b) has assumed all obligations and liabilities of
      Assignor-2 arising for the Santa Rosa and San Rafael Centers and such
      future Centers that the parties develop under or related to the Agreement
      arising on or after February 22, 2000.

      4.    ASSIGNOR-2 REPRESENTATIONS AND WARRANTIES. Assignor-2 represents and
      warrants that no services were provided under the Agreement as part of the
      Santa Rosa and San Rafael Centers before August 1, 2000, and, thus, no
      tail insurance for prior periods is required.

      5.    TPMG CONSENT. TPMG hereby consents to the assignment and assumption
      described in this Assignment and Amendment.

      6.    NOTICES. The parties hereby agree that all notices regarding the San
      Rafael, Santa Rosa or future sites required under the Agreement to be
      directed to Assignor-2 shall henceforth be directed to Assignee-2 at the
      following address:

                           USCC - USCMC PARTNERSHIP
                           700 Ygnacio Valley Rd., #300
                           Walnut Creek CA  94596

      7.    PAYMENT BY KP. The parties acknowledge and agree that all payments
      due and owing from KP to Assignor-2 pursuant to the Agreement for the
      Santa Rosa and San Rafael Centers and such future Centers that the parties
      develop shall hereinafter be made to Assignee-2, provided, however, that
      KP's payment (a) to Assignor-2 of amounts owing to Assignee-2, or (b) to
      Assignee-2 of amounts owing to Assignor-2, shall be resolved between
      Assignor-2 and Assignee-2 without liability on the part of KP.

      8.    BINDING ON SUCCESSORS. The terms of this Assignment and Amendment
      shall be binding on the parties' successors and assigns.

      9.    COUNTERPARTS. This Assignment and Amendment may be executed in two
      or more counterparts, each constituting an original and all taken together
      constituting one and the same document.


<PAGE>


      10.    DESIGNATION. The parties agree that, hereinafter, all references to
      USCC shall also refer to PARTNERSHIP as it pertains to obligations and
      privileges of the parties for their respective centers. The term
      "Contractor" shall jointly and separately refer to USCC, PARTNERSHIP,
      USCMC, ROMG and USCCMGCA.

                           III. ADDITIONAL AMENDMENTS

NOW, THEREFORE, in consideration of the mutual promises set forth herein and for
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the parties lastly agree as follows:

A.    SECTION 2.7. THE FOLLOWING IS HEREBY ADDED AT THE END OF SECTION 2.7:

      "The requirements of this Section apply individually and collectively to
      USCC, USCMC, ROMG, USCCMGCA and PARTNERSHIP. Further, PARTNERSHIP agrees
      to provide advance notice to TPMG of any intended material changes in the
      its partnership agreement including but not limited to the roles and
      responsibilities of the partners and financial status of the partnership.
      PARTNERSHIP also agrees to provide upon request by TPMG copies of
      financial statements of the partnership and copies of the current
      partnership agreement."

B.    SECTIONS 3.1(B) AND (C) ARE HEREBY DELETED AND REPLACED WITH THE
      FOLLOWING, EFFECTIVE AUGUST 1, 1999:

      (b) Each year during the term of this Agreement, Contractor shall
      determine the projected annual budget ("Projected Budget") for facilities
      where Services are provided to Members pursuant to this Agreement. The
      Projected Budget for each such facility for the first year of this
      Agreement is set forth in Exhibit 3. Thereafter, Contractor shall submit
      the Projected Budget for each facility to TPMG for approval no later than
      three (3) month(s) prior to the anniversary date of the opening of each
      such facility. The parties shall agree in writing to the opening date of
      each facility covered under this Agreement for purposes of establishing
      the annual Projected Budget for each such facility location for the
      following budget period ("Budget Year"). The Projected Budget for each
      facility shall set forth CONFIDENTIAL TERMS HAVE BEEN OMITTED AND FILED
      SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION The Projected
      Budget for each such facility shall also set forth CONFIDENTIAL TERMS HAVE
      BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE
      COMMISSION at the relevant facility for the Budget Year. CONFIDENTIAL
      TERMS HAVE BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
      EXCHANGE COMMISSION shall be agreed upon no later than one (1) month prior
      to the beginning of the applicable Budget Year. If for any Budget Year the
      parties are unable to agree upon the Projected Budget for any facility,
      the matter shall be resolved pursuant to Article 8. Until such time as the
      matter is so resolved, the Projected Budget for such facility shall be the
      Projected Budget for such facility for the immediately preceding Budget
      Year.

      (c) KP will pay an amount equal to the CONFIDENTIAL TERMS HAVE BEEN
      OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION
      provided to a Member in accord herewith. CONFIDENTIAL TERMS HAVE BEEN
      OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION
      as identified in the Projected Budget. Quarterly, the parties agree to
      review CONFIDENTIAL TERMS HAVE BEEN OMITTED AND FILED SEPARATELY WITH THE
      SECURITIES AND EXCHANGE COMMISSION during the previous three-month period
      to determine CONFIDENTIAL TERMS HAVE BEEN OMITTED AND FILED SEPARATELY
      WITH THE SECURITIES AND EXCHANGE COMMISSION for the remainder of the
      Budget Year. Such adjustments shall take into account in the favor of KP
      any volume of patients which were not able to be provided access to
      services by Contractor due to staffing unavailability or other causes
      reasonably within Contractor's control. To the extent necessary to cover
      CONFIDENTIAL TERMS HAVE BEEN OMITTED AND FILED SEPARATELY WITH THE
      SECURITIES AND EXCHANGE COMMISSION that are attributable to the patients
      contained in the Budgeted Cost (outlined in 3.1(b), above), maybe added to
      the Budgeted Cost. Discussion of the proportion and amount of CONFIDENTIAL
      TERMS HAVE BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
      EXCHANGE COMMISSION.


<PAGE>


C.    SECTION 3.4(B)(V) IS HEREBY DELETED AND REPLACED BY THE FOLLOWING,
      EFFECTIVE AUGUST 1, 1999:

      (v) Regular Medicare. If Contractor provides Services to a Regular
      Medicare Member, then Contractor shall submit the bill directly to HCFA.
      Upon receipt of a copy of the Explanation of Medicare Benefits and an
      invoice, TPMG shall pay Contractor any applicable Medicare coinsurance and
      deductible amounts, and any amounts due for Services that are Covered
      Benefits but are not covered by Medicare. Contractor shall not assert any
      claim for compensation against Regular Medicare Members for
      Medicare-covered Services, and shall not assert any claim for
      compensation, other than for the applicable Medicare coinsurance and
      deductible amounts, against TPMG for Medicare-covered Services provided to
      such Members. Contractor agrees to accept, as payment in full for Services
      provided to Regular Medicare Members, (a) the applicable Medicare payment,
      (b) the amounts paid by TPMG for the applicable Medicare coinsurance and
      deductible, and (c) the amount paid by TPMG, if any, for Services that are
      Covered Benefits but are not Covered by Medicare.

D.    EXHIBIT 3; EXHIBIT 3A (HAYWARD) AND EXHIBIT 3B (STOCKTON) ARE HEREBY
      DELETED AND REPLACED BY THE ATTACHED EXHIBIT 3A (HAYWARD) AND EXHIBIT 3B
      (STOCKTON) EXHIBIT 3C (SAN RAFAEL) AND EXHIBIT 3D SANTA ROSA):

E.    SECTION 4.1 IS HEREBY DELETED AND REPLACED WITH THE FOLLOWING:

      "4.1 TERM. This Agreement will begin on the Effective Date (specific to
      each Center), and will continue in effect for three (3) years for the
      Hayward and Stockton Centers and five (5) years for the San Rafael and
      Santa Rosa Centers, and such future Centers that the parties develop. This
      Agreement will thereafter automatically renew for each Center for
      successive five (5) year terms based upon each Center's initial effective
      date, unless terminated in accord with Sections 4.2, 4.3, or 4.4, below.
      Further, if either party desires to allow the Agreement to expire at the
      end of the initial or any subsequent term, the party shall give written
      notice of such intent to the other party at least One Hundred Eighty (180)
      days prior to the end of that term."

F.    SECTION 9.5 IS HEREBY DELETED AND REPLACED WITH THE FOLLOWING:

      "9.5 ASSIGNMENT. Subject to the provisions related to successors set forth
      below, neither this Agreement nor any duties or obligations under this
      Agreement may be assigned or subcontracted by USCC, USCMC, PARTNERSHIP,
      ROMG and/or USCCMGCA without the prior written consent of TPMG. TPMG
      agrees that such consent shall not be unreasonably withheld. CONFIDENTIAL
      TERMS HAVE BEEN OMITTED AND FILED SEPARATELY WITH THE SECURITIES AND
      EXCHANGE COMMISSION Any material change of ownership or control of USCC,
      USCMC, PARTNERSHIP, ROMG and/or USCCMGCA shall be deemed an assignment of
      this Agreement requiring the prior written consent of TPMG. If DHS or a
      Medi-Cal Plan's approval is required by law or Health Plan Medi-Cal
      Contracts, assignment or delegation of this Agreement shall be void unless
      prior written approval is obtained from DHS and/or such Medi-Cal Plan."

               THE REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK



<PAGE>


IN WITNESS WHEREOF, the parties have caused this Assignment and Amendment to be
executed by their respective duly authorized representatives as of the date set
forth below.

<TABLE>
<CAPTION>
THE PERMANENTE MEDICAL GROUP INC.                             RADIATION ONCOLOGY MEDICAL GROUP, INC.

<S>                                                          <C>
By:  /s/ Dennis Ing                                           By:      /s/ Harry Newman
   ----------------------------------------                      -------------------------------
     Dennis Ing, M.D., Director of Services Planning          Name:    Harry Newman, M.D.
     TPMG Medical Services Planning & Contracting                  -----------------------------
Date: 8/28/00                                                 Title:   President
      -------------------------------------                         ----------------------------
                                                              Date:    8/30/00
                                                                   -----------------------------

Reviewed By:   /s/ Bellinda Rossmiller
             --------------------------------                 USCC MEDICAL GROUP - CA, INC.
     Bellinda Rossmiller, Administrator
     Med. Svcs. Planning & Contracting Support                By:      /s/ Barry Tepperman
Date:  8/30/00                                                   -------------------------------
      -------------                                           Name:    Barry J. Tepperman, M.D.
                                                                   -----------------------------
                                                              Title:   Medical Director
                                                                    ----------------------------
                                                              Date:    8/31/00
                                                                   -----------------------------

                                                              USCC HEALTHCARE MGT. CORP.
                                                              By:      /s/ R. W. Padelford
                                                                 -------------------------------
                                                              Name:    Richard W. Padelford
                                                                   -----------------------------
                                                              Title:   President
                                                                    ----------------------------
                                                              Date:    9/1/00
                                                                   -----------------------------


                                                              USCMC-USCC PARTNERSHIP
                                                              By:/s/ US Cancer Management Corp. Managing Partner
                                                                 -----------------------------------------------
                                                              Name:     W. Brian Fuery
                                                                   ------------------------------
                                                              Title:   President
                                                                    ----------------------------
                                                              Date:    8/28/00
                                                                   -----------------------------
</TABLE>